But, personally,
I would have waited for them to ship, a motor shortage isn't that big of a deal, it happens rather often,
or just bad management on happymodel's side, since it's them that build and send it to them,
For the "we are sorry", I think it's just that they might have a policy where they cannot like refund X% of a purchase for any reason, so they probably thought that since you where clearly upset, simply saying "we are sorry" would have been less offensive than "sorry but we cannot give refund you a part of your order, company policy".
For the "send only the goggles then the eco", I also quite often had this issue, with other stores, but mainly because I forgot to remove something from my cart, where it was either a full refund or nothing,
and one of the rep once told me a lot of the software they use simply cannot only remove one of the items, tho I don't know if he made a generality about a minority or if it's actually like that, since he was the only one who talked about that, the others just said that they can't
Has for them saying the eco is in stock even if it isn't, I guess it might be something like an intern messing up or a software bug/slow website, so it's hard to justifie, but it's certainly not some kind of evil shady behavior in my opinion
So I don't think they are actually hiding anything else than maybe bad management, I don't mean that they necessarily had the best behavior, but I don't see anything you said has abnormal subpart maybe, but not abnormal