Complicated question! Here's my thoughts:

Fitness and general health are different things. Fitness can help keep you healthier regardless of weight.

I think someone with a lot of muscle can nudge their way into the overweight BMI category while still being healthy, but I think most people in that situation are serious enough about their sport that they are already using different metrics and measure body composition instead.

Obesity on the other hand, would be incredibly difficult to achieve through muscle mass. Dwayne Johnson is often used as an example, but he is just barely over the line for obesity. And I think most people that use this excuse know that they don't look like The Rock. There is a lot of science to support that health will deteriorate faster in this category.

Think of BMI like the expiry date on a jug of milk. It doesn't go bad the exact second it strikes midnight of the expiry date, but you significantly increase your risks the further out you go.

I run 3x/week, weight lift 2x/week, and if I have extra time and energy for it I'll also do something just for fun like hiking or step aerobics. I enjoy cardio a lot more than weight lifting, but have accepted that I need to be doing some form of strength training to maintain my health as I age.

I'm about to start stage 4 of new rules of lifting for women, so about 16 weeks in. It's been a few years since I've followed a weight lifting program, and so far this has been a good beginner's program that's been easy to adapt to a home gym and a 2x/week schedule. There's another 16 weeks to go and I am finding that I am feeling excited to move on to something new. I might try Sohee's Year of Strength 2.0 next.