I get the sense that you (& many others) believe that GM should have acted as a regulated bank ("know your customer" rules), as a regulated securities rating firm, and/or as an authoritative moral inquisitor & judge with regard to NKLA.

GM is none of those. (And they were not proposing to acquire NKLA, for "due diligence" to apply for that reason.) They are a car company. Their execs' duty to GM shareholders is to not stupidly squander GM's money. The contract was a "win or wash" situation for GM - so that duty was fulfilled. They don't have to even do - let alone produce - a written analysis. The same goes for GM's contracts with the supplies of tires, floor mats, wiper blades, etc. for the cars they assemble.

Certainly one can accuse GM of acting rather uncaring and sleazy with regard to NKLA. Nothing special about that - most older people (at least from parts of the U.S. where the auto industry is concentrated) could tell you that all of the big auto makers got over their "Don't Be Evil" idealism many, many decades ago now.