The definition of likeness rights vary from state to state and from country to country. It's a legal battle best left alone, unless you have clear permission from whomever will fight against you (such as direct decedents or a personal estate) or the person has been deceased for a long time. For example, I think by law in California you retain personality right for 70 years after death, not sure about other states.
Ahh, I dont know how it all works as its completely different in the UK. I wasnt suggesting they do it without permission, they could seek permission from Majels family. I think it would be a really nice touch for the fans and something to honor such an important lady in our beloved franchise!