To be clear, I do not consider Blink to be a hostile fork. I wish the Blink developers good luck & godspeed.
As long as the license allows it and the maintainer is not burdened in any way, no?
Compare to forking to solve a very specific or specialized problem that doesn't make sense to merge upstream, like a set of changes that only apply to a very narrow audience or esoteric use-case. In such a case, it's common that changes that do affect the main project are still merged upstream and special care is done to make sure the forks don't diverge too much.