Units counting as the wrong class

You can see in this video by Hafu, she puts in a Swain with no items and gains glacial buff. He also freezes a target in the next fight, so it does seem to be counting him as glacial.

https://youtu.be/q-8TaRczQaI?t=2075

I also know that a streamer (I believe it was Dog?) had a game recently where Yuumi couldn't be placed onto a Cho'Gath because he was already considered a sorcerer. He didn't think the Cho was gaining double mana, but I can't find the video to confirm it.