Whether or not this group is violating the license (which depends on facts that I know through hearsay and cannot prove), the fact that this is possible demonstrates that there is a loophole which can be used in ways that most people who use the GPL probably wouldn't like.

Whether or not it is a good idea to try to shut down said loophole is another isssue. But the point remains that the spirit of the GPL can be abused by putting an http rpc mechanism in front of GPLed code and shipping a proprietary thin client.

Cheers,
Ben