Ok,
Intellectual rights can be interpreted in many ways in a court of law. What angle of infringement has been violated. What were the violations intended for. Was there no attempt to contact the owners and license holder for explanations.
Most of this can be disputed in court. Lawyers make the difference here. CBS/Paramount have some of the best. So, if you wish to tread on there rights, you had better be prepared for a nasty battle (in which you are unlikely to win).
Now that I got all of that out of the way, the issue with copy right protection can be laughable when exercising something called "free interpretation". We are all free to interpret anything any way we wish. But when you charge a fee for that interpretation, you become liable for it's content. If your interpretation closely matches someone else interpretation, you have to prove that you were the first to have created it. Once that is established, everything that comes after can be considered plagerism if in lieu of charges were incurred.
Now, as for Excalibur, the content can be considered plagerism. However, no fee has been incurred from the interpretation of Star Trek, in and of it'self. Therefore, CBS/Paramount can, at will claim right to this product, but would have to drag everyone to court and convince the judge that this is in fact the case. That is, in it'self, A HUGE WASTE OF TIME AND MONEY. Also, CBS/Paramount encourages projects that promote the Star Trek franchise. This promotes better sales of merchandise and services. Therefore, no need to worry about the future of Excalibur. In fact, if Excalibur did go payware, CBS/Paramount would, most problebly, support such a venture and would want a "piece of the action" so to speak.
It comes down to economics. Anything CBS/Paramount might be able to make a buck off of, they would most likely, be interested in pursuing it. Even encouraging it. Even going to court over copy rights would not be in CBS/Paramounts best interests. In fact, has anyone seen a law suite from CBS/Paramount to any up and coming game producers? You won't find a single one as far as I know. Food for thought......