I didn't think Nos had a policy on talking about other servers, just not spamming people and /world to go to theirs. I know the server the OP mentioned has no policy and Nos was talked up quite a bit on their forums. The two servers aren't in competition.
Holmes wrote:1. corecraft is TBC, so they have some different customers 2. corecraft is going to be utterly shit. they wont script anything inbetween lvl 1-58 and you can insta get 58
Why would you want to spend time playing non TBC content on a TBC server? Serious question.
Shoot for the moon, and if you miss you'll hit the stars <3