There are two major issues with the above...
First what does a person's weight have anything to do with this?
level of threat... my sister is small. If she walks in to a strange or threatening situation with a 100lbs person she will feel less threatened then a 300lbs one... I am well over 300, almost 400lbs, and I know I am a big teddy bear, but if you don't know me you might think me threatening looking.
A 300 lb person isn't any or more less dangerous than a 100 lb person depending on the circumstances.
correct, but when someone out weights you 3-1 it is far scarier...
A 300 lb. person isn't any more likely than the 100 lb. person to be the transgender boogeyman that certain, shall we say, extremists, want you to be afraid of.
I'm not afried of boogeymen... I'm afried of monsters that are far too real.
Second, I'm not a guy. The 300 lb. person in your example isn't a guy if she's in the women's restroom. Transgender people are not "choosing to identify" as a gender...they are that gender.
now this is going to get not pretty, but everyone is born with physical markers of gender. Each gender looks a way. If anyone finds that the mental and physical gender do not match up I am sure that is 100 types of hell, and I don't want to make life any harder on them then good old mother nature already has... but you don't walk around with people seeing only your 'true mental self' they see what you were born with.
3 seconds, you have only the books cover to go by... it sucks, it's not how we want the world to work, but it is...
3 people born men... all three 300+lbs all bald with tattoos... and all in pretty neutral clothing. 1) is a happy go lucky straight guy who really had to go and the mens room was out of order, so he thought he would just duck in and out quick... 2) is a very nice and friendly trans who was born male but sees himself as a woman, but can't afford surgery... 3) is a scary monster, he is going to take advantage and possible injure, or kill the next little girl that stumbles into the bathroom...
the problem is that no one can tell the difference, all three are "Man in the womans room"
I assume that you understand that.
And there is an easy solution - remove unnecessary gendering of restrooms.
exept if it is ok for people to share a non gendered one, that what is the harm in going to one that is for your physical gender... obviously there are people on both sides of this... and a compramize may be impossible, but it is a real complicated issue that people like to pretend is just people being jerks... (Mixed with people on both sides really being jerks)
Its a bathroom - everyone needs to poop and pee, it all stinks, and everyone needs a place to do it. That's it, that's as complicated as it needs to be.
if that where true then the issue would be solved with 'just use the one that matches physicly...