I love Sourcehut, but Sourcehut's only competitive right now in the indie/free software enthusiast market. I doubt Gitlab views them as a major threat.
Much like Sourceforge isn’t and Bitbucket is not the same sort of competitor or threat as a couple of years ago. The private version that is sold (Stash?) could be though.
It's not the best comparison. Gitlab is VC-backed, whereas Sourcehut aims for slow, sustainable growth. Plus, the UX decisions of Sourcehut are so drastically different from Gitlab/Github that it doesn't threaten existing customers very much.
