I have never been tilted or looped ever by spacing n-air or b-air. There is little time to react during these attacks, and the shield stun (unless p-shielded) is a bonus. Ike comes down fast enough to jab immediately if they want to try and run at us again. But I do agree with you that f-air is one of the worst options to use vs MK.
It sounds like you haven't played a MK who is fully aware of his shield options. If you hit his shield or are GOING to hit his shield, it's a loop. If by spacing you mean not hitting him at all and just throwing it out to bait him to run into punches repeatedly, then sure, that's a thing.
I wouldn't expect it to work consistently though, as if the MK catches on and just runs up to shield your nair, you're looped again. It's not a strategy you can base your gameplay around, not in this matchup.
And a back throw has options even at high percents? Other then dash attack, you're not going to punish MK much after the throw. Like Red say, count the jumps either way, and you'll be fine.
Again, for Nair, high risk for little reward. Harder for you, easier for him etc. You don't necessarily need to follow up much after the throw, pummels and the throw is 10%+ for a stuffed approach is certainly good enough. Not to belittle nair, but it just can't be relied on here. MK is not a character you can expect to get any prolonged combos on like Snake anyway, you pick away until you can get the kill.
Pivot grabbing is way too predictable in my opinion. Yes it can be seen as a surprise when the opponent rushes at you only for you to pivot grab, however it can become very predictable. Against speedy characters like MK or Sonic, if they are pressuring you, you may not even have time to pivot grab. Also, if you do whif the pivot grab, you are easily in for a world of hurt. You honestly think any good MK will be pivot grabbed that much? That MK was an embarrassment. Ike doesn't have the best grab range so timing is very critical to that component as well.
Predictable is fine (as long as it isn't PUNISHABLE), as it can lead to your opponent mispredicting (is that a word? rofl).
I think your misunderstanding is from not realizing how lenient the PG range is, how short the cooldown is, and how small a window of vulnerability you have to be punished.
If you whiff a pivot grab from the proper distance, it's completely safe while still being able to grab attempted approaches, as well as being able to grab the attempted followup punishes.
The MK was fine, you don't have to be a prick to try to prove a point, unless it's wrong I guess.
I didn't know MK's only approach on the ground was dash attack and grab...gee whiz. I must've missed the section on short hop aerials, spot dodging, and what not.
MK's quick dash attack and grabs are a couple of Ike's biggest problems in the MU. Find a way to help deal with them, and the MU is that much easier. Know what happens when a MK runs up and side dodges your pivot grab? You get a free jab because your CD is faster.
Also, how is a short hop aerial a ground approach?
When used properly? N-Air is unpunishable if used properly. D-air is a good killing move when used properly. F-smash works wonders when used properly. See what I did there? It's impossible to make every move applied perfectly, and there will be error. Now you can say that the risk and reward for PV is less than other moves, but I still think it's easy to read and punish.
Not really a relevant analogy, because you're basing it on the misconception that PG is easy to punish.
It's good to know we have another option, but MK can simply run and spot dodge if they want, leaving us open. Oh but wait, then that means we can sit there and jab...oh but what if they shield it? Yeah, it makes for a 50-50 game perhaps, rather then something in MK's favor when it comes to that part of the match, but you are still ignoring MK's short hop approaches. On paper, it's good, but in application, timing your pivot grabs correctly is tougher then it looks. I'll definitely look to incorporate it vs speedy characters, but if we're looking simply at damage output vs MK, jab is better.
Again, the CD on PG is faster than even a MK spot dodge, and you'll be able to jab him if he dodges the grab unless you do it late or too close.
I never ignored his short hop approaches, as they aren't difficult for Ike to deal with. If MK relies on his aerial approaches, he gets outspaced by Ike's better aerial range; a great thing to force him to do.
Since you seem against PGing enough to argue about it, I'd suggest playing some MK friends and having them dash in repeatedly to realize just how effective it is at reading approaches.
Edit: As for the whole rock/paper/scissors analog going on, you could view PG as a 4th element in the equation that counters both rock and scissors and is not effected by paper.
Edit2: Thinking again on the CD on PG against a MK spotdodge situation, I actually can't picture a situation where this applies with a properly spaced PG. The distance MK goes from a dash attack or grab is enough to get him grabbed, but spot dodge doesn't give him the forward distance for anyone to get hit, so it's basically a neutral situation. So he's not dodging the grab itself persay, but nobody can be punished directly from the situation regardless.
