Its not the same mount.
If they give new era people /legacymark then by all means complain.
If you look at SE's development history equipment wise you will see its very common for them to reskin/add (unmask) small details to equipment.
If you think they were just going to develop a Goobbue mount for people who play in a few month time period and really not reuse the model at all... well now you know what to expect in the future.