It's not a direct connection, but trying to say a dwarf planet isn't a planet, when it's got the word planet right there, is generating the kind of semantic confusion that, carried forward, would lead to the conclusion that people with dwarfism aren't people. The -oid suffix already conveys "is almost the thing, but not quite," such as in words like humanoid, asteroid, android, and (most importantly) the aforementioned planetoid. Making planetoid the official word for "is in ways like a planet but actually isn't" would have been working with existing etymology, rather than creating needless confusion.