1) Because it was just one weekend of work. Not everyone might continue working on/at the startup after the initial weekend. Would be weird if a fifth of your startup is owned by some guy who helped out one weekend, even if that weekend was the very first weekend.
2) They totally could, and Bobby did, right? There is the question of IP though. What parts of the IP are of Billy's LLC? I'd agree that the code made that weekend is not, it's bound under whatever the team agreed to. But the idea of the company might really be Billy's, even if that conflicts with the competitions rules or spirit a judge would still have to rule on that.
Dick move by Billy, but the end result is only a wasted weekend.
Serious question- does the team then negotiate new terms after the weekend for those that do want to stay on-board? Who holds the 98.4% in the meantime?
The impression I got was that the 0.4% was a guarantee for what you walk away with. If you stayed you would work out ownership of the whole thing with the rest of those who stayed to build the new startup.
The guy didn't belong in a startup weekend. The team at the weekend is supposed to own/share the results. Not some guy who can't recruit engineers and uses startup weekend to defraud the real talent to promote himself.
Dick move by Billy, but the end result is only a wasted weekend.