Since the process to make toys can start years in advance of a product landing on the shelf I'd guess this is a pre-lawsuit design so Hasbro probably got permission. That lawsuit from what I understand stemmed from the GI Joe team not realising they needed to ask permission to do a G1 Jetfire toy. The Transformers team apparently always asked permission first. Only now thanks to the ruling of dismissed with prejudice they no longer need permission at all.