IMHO, there are two things:
1) I think it's bad manners to tell(or even suggest) the owner of the website what he should ou should not do with his website. It's his property, he does with it whatever he wants, however he wants... I wouldn't like to be told how to handle my business.(And I'm pretty sure almost nobody here would either). If doing this or that is a bad business decision, that's for the owner to decide and collect the profits or pay the losses resulting from that decision. Besides, telling someone to refuse money from a sponsor it's easy, when you're not the one who lives from this type of payment.

2) Anyone who uses a little bit of logic knows that any seller of "trading systems" is a scammer, since it doesn't make sense to sell something if you know how to make money in the market. So why get offended by a poor guy whose only current option in life it to sell scams? Just let the guy pay for us being able to use the site and if anyone buys that shit, that's their problem. Even for those who do get offended, the guy may be calling you names, but he is giving away his money to you in a way, since you're using a service that he pays for, so... that's got to count as a "kind of" revenge.