ML has seen the consequences of paying back with your luck on other people so I believe it's natural for him to try to talk an acquaintance out of getting into it. He was about to discuss his coworker's concerns with him further at the office before that coworker told him to forget about it, so he'd be a hypocrite if he actually let the man take the loan instead of asking him to rationally consider the consequences and assess his options. I don't see how any normal human being would let his friend get into that sort of loan and mess up their life for the sake of money...
Besides MC hasn't provided any actual help for ML yet. He took that credit card and is using it in order to be able to keep going back to the office hoping that he'd bump into that pharmaceutical company's manager or whatever; and everytime he does, it is ML helping MC out, treating him, saving his ass from mad or horny clients, buying him sweets, etc...
Isn’t ML a little too arrogant? The coworker knew what he was getting into, he accepted the terms, but because ML interrupted, he now thinks that this is a scam. Moreover, ML is a hypocrite. He himself has that credit card, does he think no one besides himself is in a desperate situation, or smart enough to not use it all the time? It is also true that MC helped him a lot but he disturbed his business.