I have/had no idea that something like I posted was against the rules, even less so in my own thread
That's on you--you've been around long enough that you should have read the rules by now. Aside from that, what section did you post that in? It doesn't say in the screenshot you linked to.
Now tell me, how does this deserve a 60 days ban? 60 days? When this place (the forum) is all over shitposters, everywhere? This is unreal... unbelievable actually how honest members of this forum are f***** - congrats mods!
You're right, there are indeed shitposters everywhere, but the offer you posted encouraged them to keep bumping your thread to the top of whatever section you put it in, with zero-value posts. But that's why I asked what section the thread was in. It's still against the rules, but if you had it in a garbage section (like altcoin bounties or Games and Rounds, etc.) it probably wouldn't have had much impact on forum quality anyway.
In any case, the 60 day ban is fair. I've seen other members get the same punishment (or it could have been 30 days) for doing exactly what you did--but again, it's in the rules, so there's really no reason for you to be upset about the consequences.