Do AMD, Intel, Nvidia, HP, Lenovo, Ford, Honda, and so on send a cease and desist letter to every publication that mentions them in passing during a review of a similar product? Product comparisons are inevitable. If I review, say, a Sony Smartwatch, you bet your ass I'm going to compare it to a Pebble and an Apple Watch, otherwise there's no real frame of reference.
IMAX's lawyers are clearly overreaching here.