If you take 30 seconds to Google you'll find a bunch of sources that indicate the low percentage of men in nursing is nuanced. It's not just toxicity or gatekeeping.

Examples:

"Research indicates that ideas of masculinity prevent men from pursuing a career in nursing." - https://www.npr.org/2018/10/02/653570048/why-more-men-dont-g...

"The problem is that notions of masculinity die hard, in women as well as men." https://www.nytimes.com/2017/06/24/opinion/sunday/men-dont-w...

"Some tasks require getting in a patient’s personal space and some patients may prefer to request a female nurse." https://www.rasmussen.edu/degrees/nursing/blog/men-in-nursin...