Okay there's SO much to unpack here.
"Kin" is not a verb.
You can't "kin assign" anyone, especially not people who aren't Otherkin in the first place.
Being affected by a character's death =/= having been someone who was close to them. The show was written to make her death affect you. Even if it's uncharacteristic of your friend to be upset about character deaths, that does not mean anything but that perhaps it struck a chord that things don't usually hit.
I have literally never met a RWBY fan in my life who wasn't upset about Pyrrha's death and isn't still upset to this day.
That said, it's certainly possible that you're right. But it's definitely still strange to "assign" characters to your friends who aren't Otherkin (though arguably worse to do so to your friends who are) and I would certainly recommend against doing that in the future. People's souls don't listen to your will, and you cannot "assign" them something that they aren't. You can associate someone with a character, but that doesn't assign them anything.
- Fae