Brace yourselves for gravitational waves

[Jackalope]

I would imagine that if there had once been life in the neighborhood of the merger, there isn't any longer..

Indeed, and 20-35 solar mass progenitor stars are big nasties throughout their lives.  So, anyone close would already have been zorched by prior misbehavior.

Well... Close is a relative term. Enormous stars like that certainly are going to bathe their immediate neighborhood with radiation, but the merger is many, many orders of magnitude more energetic, and the calamity would be less localized, I would imagine. I mean, the merger is even many orders of magnitude more energetic than when they originally collapsed, and that would have been bad enough.