The mod took down my post without any comment, reply, or reason.

This is definitely enough reason.

It also opens up an interesting debate about what is appropriate. While the mod action is understandable (they don’t want rival communities), it’s a bit of a misuse of mod tools to delete it in my opinion.

Then separately they’re harassing you by following you round downvoting everything you post. That’s the sign of somebody unhinged. They are able to compartmentalise actions that occur inside their community from the wider Lemmy.