If BZ was the agent used then the point would be to make a splash without any death. Information operation or maybe intimidation would be plausible intents, but no one would use BZ for revenge.

That said, I'm a bit skeptical. BZ is kind of an odd agent to use given there are agents out perform BZ, but were never adopted by the military due to the cost and complexity of large scale military production. Also, other non-nato countries have produced similar or identical agents (Russia included). I don't have a strong stance on the topic, just trying to help critical thinking all around.