Why was this useage of "queer" offensive?

The thing is that to you there is a difference to my former neighbors who happened to be black they used the construction colored people and colored all the time. Now they happened to be old and retired and their usage, while anachronistic to younger folks, wasn’t meant in any way to be offensive.

At some point context has been willingly lost in order to seek offense.

Summary

It’s a bit like the silly Latinx that some on the left use.