I don’t think that is ‘tin foil hat’ at all.
Very plausable in fact.
Social contagion is how these incidents are provoked.
No direct contact with a shooter is required. Just intense broadcast messaging and passing suggestions to the right circles.
Marginal individuals hear and respond to those suggestions. And each publicized response lowers the threshold of messaging needed to provoke the next response.
A variation of mass-market and directed channel advertising is how it can be done. And, yes, I believe that members of the "Deep State" are actively engaged in such things.