GitLab's DMCA policy is not substantially different from GitHub's. Finding an example of YouTube-dl on GitLab doesn't mean GitLab doesn't comply with the DMCA, it just means RIAA hasn't sent them a DMCA notice yet. Regardless of how vocal you are you won't convince a company with US operations to not comply with the DMCA.

Rather than getting mad at companies for complying with the law of the country they operate in, why not support organizations like EFF that are actively working to change the DMCA?

https://www.eff.org/issues/dmca