RMT-Named Characters Can /shout???

[Pintsized]

So why is this latest RMT activity made worse by their being able to use /shout on their presumably 'free trial' accounts, and why has SE still not prevent 'free trial' accounts from spamming party invites.

No, I don't believe there are 'stolen' accounts, they appear far, far too frequently for them to be those, they have far more value to RMT to sell the accounts or use as farming bots.

[Canadane]

Believe it or not, RMT actually do buy the game.
This is how you see a gaggle of level 50 thaumaturges teleporting around. Trials can't hit level cap.

[Atoli]

Free Trial characters can't shout :0
Are you mistaking normal chat spam for shout spam?

[Chat Restrictions]
-The chat options /shout, /yell, and /tell cannot be used by Free Trial characters.
[Party Restrictions]
- Free Trial users cannot invite other players to their party.

Anyone who buys from RMT sellers is at risk of having his account compromised. And seeing how RMT is still a thing at all, it's obvious quite a lot of players participate in it. Other than that..well, RMT spam was a thing even before the free trial existed. Might be that they just went back to how they did it before - creating new characters on stolen accounts and actually paying for advertising accounts.