Honestly? If Rowling was just a transphobe, I'd probably still consume her content. It's the fact that she is loudly and actively using her fame and fortune to attack trans rights that makes me unwilling to continue purchasing her intellectual properties.
I have trans family that enjoy Harry Potter, and continue to purchase HP stuff. My partner is a massive HP fan (like, display cabinet full of the stuff). I'm not going to disown them for it any more than my vegan friends don't disown me for continuing to eat meat. Some of my favourite content creators probably have views that I vehemently disagree with as well, I just don't know it yet. And it would be really hard for me to distance myself from some of their works if I did learn of whatever gross immorality they may have, because I derive a lot of happiness from the things they create. But I can't stay hyper-vigilant to every potential wrong lurking in the shadows of my life, because that's an easy way to end up stressed out, exhausted and miserable.
Having said that? I do know what Rowling does with her time, money, and energy, and it's really easy for me to not contribute to it. So I don't. But I'm also not going to hate on folks who have HP as their comfort media, especially with the way the world is today.