Yes they're allowed to use the map as it's published to the steam community and Xq allows everyone to use it. But there are some PERPHeads references to the map so they can go suck a fatty with their map
If the map is put out to the public and is not actually copyrighted (aka actually payed for to prove its ours) then yes. There's not exactly a legal basis behind it, but I'm sure we don't want them using something without at least giving credit.