Where my thinking is at right now, though, is that Gitlab has just tangibly demonstrated that they don't deserve a great deal of trust, and so I'm not inclined to trust any opt-in or opt-out choices.
Even if they're effective at the time they are introduced (which I don't really doubt they would be), I am not comfortable in relying that they won't change the deal in the future.
Source control is a particularly good example when it's the core IP of your company at stake, and engineers--who can sometimes be a bit prickly about these things--are making the decision on which product to use.
In this case the reaction to me seems overblown, as Gitlab AFAIK has been a well run and particularly transparent company. I felt the same way about the recent reaction to Gitlab saying they want to stay out of the politics of passing moral judgement on every repo they are hosting, which to me seemed exactly right. To be clear, I'm not and have never been a Gitlab customer, so I'm not basing any of this on any personal experience the quality of their product.
Now speculating on how they might do something in the future which impacts self-hosted instances, assuming the worst, and declaring it will mean switching providers... I think the comment would be better off just saying something like; "I'm looking at the way Gitlab is handling this issue and it makes me no longer trust them with my data, so I will be going elsewhere" -- just without the rank speculation.