I believe the point is if google was illegal where you live, it would be illegal if Google said "hey you can still reach us without the big man knowing by using our partners ‘borgVPN’ ". BorgVPN could be in trouble for the partnership, even if they aren’t the actual banned service.

There’s a multitude of reasons any business with critically important data to their customers (lawyer, accountant, etc as you mention) should not roll their own system to save a couple hundred dollars a month…