Ofcourse he can pay with other currencies.
It is not off topic, OP tells about CrowdCoin with is a crypto currency, and is willing to pay with crypto currency, which is all related to bitcoin.
I just can't see any problem, bitcointalk name may includes only bitcoin, but it's about all the crypto currencies related news.
At the same hand you could have said that people shouldn't talk about bitcoin cash here because it is not bitcoin, but it is probably the hottest topic at the bitcoin world right now.
mate use your brain a little bit... there's a specific place for services paid with alt coin. This section only allows payments with bitcoin. Your answer doesn't make any sense.