1. Since he tripped, he couldn't walk/run into a jump (or do anything other then trip).
2. At least you accept this possibility.
3. Why'd ya bring it up then as what he was going to do?
4. At the very least, he wouldn't be on the edge where he would be D-aired off.
5. Everytime you walk or run, you risk tripping.
I believe you only trip when dashing. I have never tripped when walking, and have been told that you can only trip when you smash the joystick. Mind you, Falcon could've even been trying to Fsmash without the cstick, and this would cause a trip.
Also, without the trip, Falcon may or may not have been hit by Fox's Dair, but I HIGHLY doubt it would've dragged him offstage.
Lastly, it's likely Falcon was going to perform an Aerial. Before I jump, I usually hit the direction I want to jump, so I can begin moving forward immediately. In this instance, Falcon did the same, and tripped before the jump.
Falcon, I really don't care what happens. In the great realm of all things Brawl, tripping has screwed me over, but I've been fortunately enough not to get owned in Tourney by it. Yesterday, I tripped into Fox's fsmash at 36%, but this ruined my momentum, and enabled Fox to turn the tide, when he probably would've otherwise lost. Momentum is very important in Brawl, and tripping kills it.
I won't mod my own Wii, as I play for fun as well as sport, but if I were to go to a tournament full of tripless Wiis, I definately wouldn't complain. You can add me to your ignore list if you want, but I think it's pretty immature and close-minded if you just ignore everyone who doesn't have the same opinion as you.
Lastly, I think that additional mods to the Wii as a tournament standard is dangerous ground, mostly for the reasons Taiki stated. I'm not entirely sure how long it would take to check for unapproved hacks, but it does take time. If there are lots of setups, or the tournament is large, this could waste valuable time. Furthermore, it would only take the minimum amount of time if no one actually modded their Wii additionally. Let's say 4 people did. Now you have to decide the consequence. One of them says they didn't remember to take off the mod to buff Charizard's weight, because they were trying to do boss battles intense, but needed a bit of a boost. Now do you DQ them for this or what? And of course, the other three now have similar excuses. You'd need a clearly defined set of consequences for this.
I'm not saying that mods shouldn't be used. I'm just saying if you're going to have it as a tournament standard, you're going to need a few more rules, and prepare to overcome a bit of controversy.