Well now that I can post again.
This MU is kinda dumb because neither character has a truly safe kill move on the other. Lucario's Fsmash won't work unless Fox make a mistake, same with Fox's Usmash. When Lucario is at Usmash kill range, 105-120% or so with good DI, he can actually kill fox pretty well around that percent.
Lucario is outcamped, but that really isn't a huge deal. Even if Lucario would hop around lasers the fact Fox has a reflector and speed kinda hampers any chance of Lucario trying to play keep away with Fox.
Lucario is better in the spacing department. He can out space Fox so if he can get up close he can space with Ftilt and jab for the most part. Phil told you about the Uthrow CG to 38%-dthrow/bthrow. It's legit, Lucario needs to buffer the throw for it to work so if you spam shine to break out so you can catch him in the middle of the CG if he doesn't buffer it correctly. Lucario could shield and regrab but I'm 99% sure he's trying to buffer the grab and is going to not catch on fast enough if he made a mistake. The grab needs itself to stale to work properly so if he starts around 20% or later you could shine out, but keep him mind he can shield grab you out of shine if you think Lucario is going to do this jump away.
The main problem a lot of Lucario's hate in the MU is how hard it is to use Fsmash, if he wiffs it Fox can get a free Usmash, also if you shield it close enough. Can;t really catch you on landing frames or if Lucario can it's kinda hard since you can stall in the air with shine and your fall speed can get you to the ground quickly. Usmash while a good punisher is not safe on shield Lucario can punish this, Dtilt, Utilt, Filt, grab, jab etc.
Lucario is going to take to the skies more than the ground, he will beat Fox in the air. I know that Fox has fair but I'm pretty sure Lucario's fair will beat it out if he throws it out so it nails Fox's feet. Uair kills are going to be rare because dair out ranges and out speeds it.
I really can't see Lucario getting shine spiked unless he makes a huge mistake. Kinda like the Wolf MU Lucario can recover high pretty well and even then catching him in the middle of his UpB isn't that easy. Speaking of recovery, your side-b is easier to catch than Falco's is, and if Lucario can get the timing down, not too hard it's just waiting a little bit, and knock fox out of side B. Still Lucario needs to get the move out at the right time, and that inself is kinda tricky.
Stages, well Yoshi's is fantastic vs Fox, Frigate on the first part is awesome. FD and japes suck for Lucario in this MU, well japes is more manageable against Fox rather than Falco but both are still a pain in the arse against spacies. I love playing on FD but even I admit it's aggravating.
I really do think this is a 5:5. Fox is a pain because Lucario has to play so awkwardly to go even in this MU and Fox still has fears of his own about Lucario in other areas.