I have spoken to spm_43030, he is unable to say where the quote came from.
I am not aware of anyone removing anything "because it advertised Rail Chat", the signature was removed because it was too large. That has now been resolved and the signature is fine now.
Chaz - no, we don't have that rule here. Obviously blatant spam isn't allowed, but there's nothing wrong with people giving their sites a mention, and we welcome that. If any staff member is removing things for that reason I will promise to resolve the situation.
I have absolutely no idea where this quote came from, even spm_43030 doesn't know, so I am totally unable to get to the bottom of it. So can we please leave it there? If I was told how the quote came about I can assure you I'd deal with it.