I got for the 'chess' business deal, strategy, tactics, planning, thinking ahead of the competition, sacrificing time and pieces to advance that pawn or take key pieces and then win the game. No bluffing, just out-thinking and studying book moves. Chess in 12 dimensions actually.
If the OP is worth his salt in the marketing game is the big variable, he believes he is good enough to warrant a $8K outlay, more than half of which goes to his co-founder to cover their time.
I've seen people study chess book moves for half a lifetime and still not be able to play a half decent game of chess. All I have to do to throw them off is play (1) b2-b4 -
50% of an MVP + cash to cover for your time + a co-founder to boot + $3K in marketing budget for your MVP is not a bad deal by many standards, and if you end up not liking the deal you can take your toys and go home and the OP is the loser.
He's betting that it works, not betting that he can screw you over.
What you would do or not do is entirely besides the point.
If you don't think this is a valid proposition, then don't do it.
Who cares who the 'candidate' is, I'm sure that anybody that enters into this will want to know before they commit to two months work, at the same time I don't begrudge the OP his choice to be anonymous for the time being.
Being (in)famous can be an upside or a downside when making an offer like this.
There are a few toxic names in the start-up scene and I'm sure that google will be able to turn up enough red flags based on name alone in those cases.