Broadcast controller = spam?!

I had an idea the other day to use a broadcast controller to contact people attending the same signal as me, telling them simply "I'm on a peaceful salvage mission and willing to share, I won't shoot if you don't" rather than saying it on global chat (and inviting everyone who wants some random PvP) so I set this up tonight. First broadcast controller I've ever ever built, first message I typed into it. I set the antenna to 500 metres, which seems like a decent radius for the job, broadcast to everyone in that radius. Which, at the time, was just me. I tested my broadcast button to see how the message would turn out.

It did not go well. See attached file.

Why would that alone get me accused of spam and placed on timeout for an undefined period?

If we're not allowed to broadcast to everyone in even a short radius, why is it an option on the block?

It's not even as if actual spammers would bother with that. Why go to the trouble of actually building a working grid in the game to send spam messages when they can just have a script log on to the server, send the message in chat and log off like they do on the likes of GTA? Is this something that's happened?