I recommend taking the higher ground and ignoring the post. In my experience, reacting to this sort of thing only leads to more problems. The reason why a person might not be specific about who they are referring to in a post is so if you confront them on it, they will have a "plausible deniability" and you will look like a fool for thinking they were referring to you.
But the problem is it is really frustrating to not be able to respond to an insult. You might find it helpful to write a response, but never send it.
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Never let the weeds get higher than the garden,
Always keep a sapphire in your mind.
(Tom Waits "Get Behind the Mule")