maybe it would be good to reply and say “Thanks for your email – right now, I am not really interested in a co-operation because X, Y and Z.”
If someone wanted a second pm from that affiliate manager, then then it might be good to reply like that. If one didn’t want to continue discussing their program they’re trying to get you to join, then I might not reply.
Most people wouldn’t take a simple “I’m not interested because” and just go away. That would be the open door for them to overcome your reasons for not joining. I hate when someone is really trying to sell me something that I’ve already told them I’m not interested in.