And even if the argument is "Well, Chooseco was trying to get into interactive media as well" I think the exact same argument still holds. Bandersnatch is proving (helping build?) the market for this kind of stuff in general. It's success is paving the way for Chooseco to follow with their own CYOA branded interactive movies / tv-shows, if they want.
And never mind that they probably still could have negotiated a deal with Netflix eventually anyway.
Basically there's nothing good about this... it's just killing goodwill, harming a potential relationship, wasting money on lawyer's fees, and distracting them for, oh, I dunno, creating quality content?