Not all of those detained because of the red shirt protests are Thai. There are two falang, one from Australia and one from England who are also in jail for breaking the emergency decree. A Thai court recently determined that these two could be held an additional seven days pending the filing of charges.
The Australian, David Purcell, was reported to have appeared on the stage at Ratchaprasong and given speeches decrying the government and praising former Premier Thaksin and the red shirt cause. The other falang is a British national who allegedly talked about looting and burning down Centralworld.
One of them, I think Purcell, has alleged that he has been roughed up while in custody. There is a photo of him in the Bangkok Post where he appears to be yelling and being held back by a Thai guard. Apparently he doesn't know how to behave in or out of prison.
Seriously, it takes a special kind of stupid to get yourself involved in this to the point of being arrested. If these guys are lucky, they will be released and made to leave. If they aren't lucky, there are all kinds of unpleasant scenarios. They could spend some time in jail because I doubt they have any Thai friends with serious influence. Maybe they will find themselves as scapegoats, as its never good to talk about buildings burning, and then it actually happens.