No one is suggesting that women are forced into front line units - just that women are not barred from certain units if they choose to apply
It's not units though Dragonwoman, it's capbadges. A female can be assigned to any unit, including Special Forces, RM, Paras etc, but they can't be SAS, RM, Infantry etc.
At the end of my 24 years Service I will have spent 15 years serving with Front Line forces but have never been Front Line myself. I do a job in support of them, but am not expected to do the same training, fitness etc as them. I can fire my personal weapon just as well (and sometimes better!) and have the same knowledge of battle rhythms for example, but would never be expected to lead the battle.
I am reasonably fit but even at the height of my career would not have been able to complete (for eg) an 8 mile forced march carrying 25kg plus Rifle & Helmet, to be completed in less than 1hr 50 minutes and this is the bare minimum that is expected - it's just a test. On Ops that weight could double. Imagine the stress placed on the body.
My trade means that I have to go as far, and in the same time, but carrying less weight. It is the same for men in my trade.
One of the Regts I was at tried to insist that all personnel completed the same training tests. It was a disaster. Within months all the women were broken and resentful, some requiring treatment to this day. I firmly believe, based on my own experience, that CO's with women 'capbadged' to their Regt will expect all the women attached to that Regt to do the same as her. She would become the poster child that the rest of the women should aspire to, and when they aren't able to do so they will then be unfairly judged against her.