This is because the staff consider the bitcoin-XT currency to be an altcoin
They are correct. Bitcoin XT is not altcoin yet, but will be when hardfork of bitcoin will inevitably occur as a result of larger block size accepted in future!
Exactly. So why censor it now? Right now I can download the Bitcoin-Xt client, import my wallet from Bitcoin Core and spend my coins at merchants that use Bitcoin Core. So obviously isn't an altcoin client right now, its a usable Bitcoin client just like any other. Doesn't make sense to censor it now becuase it will become an altcoin client in the future.
Just to note by they way that my opinion is that I am for larger blocks (or a abolition of a blocksize limit altogether). However I am totally against Bitcoin-XT and they way certain developers are trying to change the blocksize. People are being mislead into believing Bitcoin-XT is different from any other altcoin such as litecoin, it really isn't different. I also think that they should remove the "bitcoin" part from the name as this is a huge part of the confusion. Mark Karpeles used to own the trademark for the term "Bitcoin" in the US I believe, maybe he should have his lawyers look into the misuse of this trademark.
Nobody prevents you for making your own forum and call it bitcoinXTtalk.org.
Then can you freely discuss bitcoin XT and move all the threads about bitcoin into the altcoin section.
Untill then, please keep the talk about bitcoin XT outside the bitcointalk.org forum.
Thanks.