I know that C2P means ILCoin is quantum resistant, but is it also resistant to 51% attacks ? But then again, is it possible to be resistant to 51% attacks?
Since ILC is not opened for public mining, i dont think it is possible that someone outside do 51% attack, so another advantage of ILC.
I know, right?

Yep, not being opened to public has its disadvantages and advantages, but i heared that team will consider public mining in the future, but you have to extra careful with this, and not hasty.Everything has its pros and cons.
When and where have you heard about this?
Come to think of it, just in case mining ILC would be allowed, is ILCoin's security enough to prove that it's really secure compared to Bitcoin?
More importantly, will it be enough to increase ILCoin's value to overtake Bitcoin soon?