Yes. However whether or not it has protections under copyright is not always clear. Likely your comment is too short and simple to be protected. But if it can’t be protected claiming to grant a license to that work doesn’t change it.
Basically by adding this note they are effectively granting a license to the work. There is no situation in which granting a license can restrict how a work (which is effectively maximum protection).
Is an internet comment a ‘written work’ though?
Yes. However whether or not it has protections under copyright is not always clear. Likely your comment is too short and simple to be protected. But if it can’t be protected claiming to grant a license to that work doesn’t change it.
Basically by adding this note they are effectively granting a license to the work. There is no situation in which granting a license can restrict how a work (which is effectively maximum protection).