How hard is it to identify a account spamming the same thing over and over then leaving. I seriously question respawns ability to see what accounts are doing....
Those pesky spammers are very annoying indeed. But use the 'mute squad' option at the Legend Select screen if you need to by pressing 'F' if you're on PC.
You can also report them by going into your inventory / Squad tab and the report button is at the bottom. Select the reason and send the report.