With regards to the non-silly part of your argument: I actually agree with everything but the last sentence of your first graf. The poster here has "a good case". Would probably even win. The problem is: if the "other founder" wants to, he can trivially drag this out over ~18 months. During that time period:
* The business is going to suffer as this guy wades through pointless legal drama
* He's going to hemorrhage money --- money that could be plowed into company development --- on legal fees
* Under normal circumstances, nobody is going to consider investing in a company that is embroiled in legal drama over its ownership
* Even if he gets a favorable outcome in court (the odds favor this outcome but do not strictly require it), he'll probably still end up conceding some degree of ownership
He's been dealt 7 - 2. He's paid the blind. I'm saying that going all in on 7 - 2 is a stupid play. If he invests 18 months in developing a new company, his odds are almost certainly better.
He doesn't have to let the other guy "win"; he has the same axe hovering over the other guy's neck. The business is tainted; maybe they can do a buyout, but otherwise, they're both going to have to walk.