No, they would on their own phones automate sending spam to the iMessage network using ble at the interface.

Or just send spam through their iPhone.

I don't get this argument that Apple making it difficult for their paying customers to send and receive messages is somehow a good thing. It's also not like Apple is helpless, they managed to shut down Beeper.

You can already use a Mac to automate iMessage. It supports Applescript.

They can already use USB rubber ducks to automate the iMessage user interface, even if they don't have a Mac.

Regardless, they would need to be a few meters from you (spec says <100m, but that’s very generous).

If they are right next to you, there are many criminal activities more lucrative than sending an imessage...

...Which wouldn’t be possible anyway, because devices using ble to communicate typically require to be paired together by their owner.