The forum is about bitcoin and anything not related to bitcoin = Altcoin which should belong to the Altcoins sections . If we create a sub-forum for Monero , we will have to create for every single altcoin out there if we want to be fair .
As Lauda said, it's no good to set a precedent for creating a section per altcoin. Then we'd need thousands of altcoin sections.
I do think that Monero is probably the best altcoin right now, since it actually does something major that Bitcoin doesn't, even if its scaling is terrible and it'll probably be replaced by a Bitcoin sidechain someday. Achieving Monero-style anonymity for everyone should be a long-term goal of Bitcoin.
Let's use market-based mechanisms to solve this putative free rider problem.
If Monero (or any altcoin) wants a monero.bitcointalk.org subdomain, its supporters must donate 10 BTC to Thermos.
That's win/win, because the altcoin gets it's own dedicated high visibility/SEO friendly subdomain, while the mothership forum gets funding at the same time as tangential content self-segregates in areas outside of the altcoin ghetto.
If we don't do this, Altcoin Jesus may take the opportunity to profit from selling more bitcoin.com subdomains, as he's already created a casino and some other goofy shit on there.