I'm not a lawyer but I'm pretty sure that hiring someone doesn't mean that you grandfather their liabilities. If that were the case the world would be chaos.
If Sonarr was the reason to reject him then it was done out of complete pettiness.
It doesn't download pirated shows, nor does it play them. It just organizes and renames and creates lists of missing episodes for files that may or may not be pirated content.
I've also seen it in the weebs and also brainwashing Japanese Corp culture.
I have a feeling because its m$ their cture dictates that they at least appear they were disgusted with his sonarr authorship.