I want some advice

[GUBU]

I'd hear his whole pitch. Listen, shit stains have a tendency to be successful. It's almost a qualification. If he's not asking for money, but he wants your expertise and I'm assuming your intellectual property, you drive a hard bargain. Whatever the project is, you want a chunk of it.

It's no skin off your back if he declines. He needs you, and you don't need him. That's a prime position to be in.

ETA: I am assuming he's starting a company or needs technical help selling his product. If he's trying to get you to buy into something---anything---My advice is the same as everyone else's.

Even if it were a business proposition yer man would still look to fuck pool over, just like Edison did to Tesla after Tesla saved his company. And given the disparity in circumstances Mike'll have the whip hand, even with a contract. Money buys a lot of justice.