Currently (as of right now) XT is Bitcoin as it operates seamlessly with the bitcoin network.
No, the XT is
pretending to be Bitcoin, but it's not.
It is extending the current protocol in its consensus-enforcing part. Because it says: after 2016-something if 75% miners have done something, we can produce larger blocks. It implicitly states it can do something the current protocol doesn't allow, under certain conditions that you call 'consensus' (which is far from the real consensus). It can disguise as an ordinary client in the meantime, doesn't matter, it won't make it Bitcoin.
It's not like protocol will be changed only if 75% miners agree, it's already changed by adding this very condition. Protocol amounts to all consensus-critical rules, implicit and explicit, that are written in the software.
Does xt pretend to send transactions on the network seamlessly now or does it actually do it?