I think the CTO's reasoning comes from that while GitLab is competitive in terms of usage and features (actually offering a more complete CI experience imo), it

I think the CTO's reasoning comes from that while GitLab is competitive in terms of usage and features (actually offering a more complete CI experience imo), it's influence is still relatively miniscule in comparison to GitHub. I wouldn't be surprised if you tried asking random people in public or in a university whether they know GitHub or GitLab and came to the conclusion that GitLab basically does not exist for many people. Especially for newer programmers, the vast majority tutorials/educational courses and whatnot probably don't even mention any alternatives to GitHub, much less an explicit reference to GitLab. I say we just give it time, GitLab as a company seems like a way more inviting environment to me and if they keep up the good work GitHub may have to start acknowledging them more.