Holdo had ZERO reason not to tell Poe the plan. What's the worse that can happen when you act so suspicious and secretive whil the general is knocked out cold and can't stop you? I dunno, perhaps a MUTINY.

Maybe this is a hot take, but I think Poe acted rationally against her... https://twitter.com/DCFlashshill/status/1259308896612683776

When he held you at gunpoint, that MAY have been a good time to tell him stuff.

Actually wait, you didn't even assure him there was a plan when he begged "PLEAS TELL ME WE HAVE A PLAN"

CAN YOU BLAME THE GUY?