Appears to be this company. Or they're using this company's name, but that would be wildly stupid of them to attempt if they want any chance at all of winning (which they already don't seem to have -- way too much prior art).
The inventor of the patent is listed on the register as Marvin T Ling. [1] The gtx.com website has a press release stating the owner and founder of the company is Marvin T. Ling. [2]
If most or all the small-time operators settle, that doesn't set precedent, though, right? A judge isn't going to look at a future case and say "well, all these other companies settled, so seems like the patent is valid". That would be absurd.
The way I understand it this is done to make the terrorists' threats more credible to other victims, not to judges. But I would also not put too much trust in judges in particular jurisdictions, such as EDT.
Appears to be this company. Or they're using this company's name, but that would be wildly stupid of them to attempt if they want any chance at all of winning (which they already don't seem to have -- way too much prior art).