I don't give a damn about infinity. If it is doable, why not? But is it? That's the only question.

I'm not sure what you mean by this, especially given your earlier focus on whether infinity exists and whether using it in physics is akin to religion. I'm also not sure what "it" is in your sentence, but it seems to be the supertask in question. I'm not sure in that context what you mean by "doable."

Then, a supertask mixes the infinite set of naturals and we are witnessing "the irresistible force acting on an unmovable object". What the Hell will happen? Will we have finite numbers on the first 1000 places? We should, but bigger, no matter which will be.

The "irresistible force" is just an empty word. And so is "unmovable object". And so is "infinity" and so is "supertask".

I'm not at all sure what this means. Can you please stop using analogies can make a specific example of how to formalize this contradiction in ZFC?

The topic is also exercised here:

http://mathforum.org/kb/thread.jspa?forumID=13&threadID=2278300&messageID=7498035

This seems to be essentially the same argument and it seems like the exact same problem: an assumption that an intuitive limit must exist. Limits don't always exist when you want them to, and we have a lot of theorems about when a point-wise limit makes sense. None of them apply here.