By avoiding the word, you avoid insinuating the target's gender is part of the issue, and/or avoid insinuating that the target is effeminate when they "should not" be, i.e. you avoid homophobia.
When HN can't tolerate such an obviously true statement such as this, yet plenty of dog-whistles supporting homophobia and racism and transphobia in this thread stay upvoted, it tells me I probably shouldn't be spending time here anymore. I don't know if I've changed or the community has changed. Probably a bit of both. Maybe it's time to grow up and move on.
IE: Describing a straight male as shrill might make passersby assume he’s abnormal and abnormal men are viewed as homosexual and it would be really awful if you accidentally did a homophobia so stop using the word shrill.
For example, sitcoms used to do this all the time. You'd have two big buff contractors or whatever talking about some work they did, and one of them would say something along the lines of "Hey Frank, that's real cute." Then they'd both realize what was said, get real uncomfortable, the canned laughter would hit, and they'd both stand up, brush themselves off and change the topic hastily.
I understand it's pretty subtle, but jokes and insinuations like this have been a regular part of (at least North American english) culture for a long, long time now.