The legal problems of the unseens couldn't be unknown at the time the classic artwork was done. That said i expect from any professional business to check on the matter before any risky release. IIRC with the release of the classics artwork something like that was said. Everything is fine with the new artwork.
As CGL put some money into that project i can't believe that this critical check wasn't done correct. Furthermore all the print products with this classic artwork is still available. If there is a legal issue, the print media would be impacted too.
But if it is no legal issue, then it must something really big on the distribution list of CGL to hold back those two classics ... and by the way many other cool classics where we have seen prototypes before ...
As i mentioned in the other thread, in amplification of your point it beggars the imagination that, given how overprotective HG is over... That R-Show... even unto suing a company who had a license from the original Japanese creator to sell transformable toys based on Macross here in the US... that they wouldn't have bought or had their lawyers request copies of 1SW, CM:M and CM:K and gone over them with a fine-toothed comb (Hell, they could have even gone on the web to see pics of Tasha K's Warhammer) and sent a C&D before the first printing's ink had dried.
That being said, I can't see any other scenario that would cause this particular sequence of events -- if it was something on CGL's side (for instance finally being able to announce the Classics in plastic), I can't imagine them ever allowing IWM to go through the expense of making the mold for the Wasp and then telling them "oops, sorry, we want to keep the Wasp for ourselves, after all."