If true, then the bad temperament can be easily bred out in a few generations, as long as folks try.

I have a cinnie with a good temperament.

His 'white snake' rule doesn't stand up, anyhow. I have produced both very sweet-tempered and very nasty albinos.
I have produced extremely docile and extremely snappy pastels, too.

The truth is, may people ignore temperament entirely in their breeding programs, and focus only on the paint jobs.