In your promotional copy for your book don't reference another writer and dis them. If they're an established author you're not going to win over readers of that author (who may be on a hiatus so you might have an opportunity to find readers)
This reading lark isn't a competition, no matter what publishers say. Yes you're in competition with other new authors but you're also their peers. If someone chooses both of you to read this year, yay to both of you. I can guarantee that if I see you dis someone I enjoy for stuff that is nothing to do with stupid life choices (dear Marion Zimmer Bradley, thanks for ruining my enjoyment of your works with your support of your idiot husband, yeah both of you are dead but it leaves a bad taste) I will not choose you over a similar writer I'm choosing to spend my time with.
I choose not to spend my time with people like this. I choose not to spend my time with authors who seem to be preaching at me rather than along for a ride with me. I'm getting too old to put up with things that drive me crazy. Instead I'm going to enjoy the ride. This is not to say that I won't put effort in but I'm no longer to overlook what is basically insulting behaviour, I wouldn't put up with it in real life, why should I have to put up with it in what I read?