Sorry the world doesn’t work like that. Ex Monarch pilots are no more loyal, skilled or experienced than the guys/girls already in the BA holding pool.
In fact those in the pool clearly wanted to join BA having gone through the process already, not simply because their own airline failed recently. How many of the people you refer applied to BA two years ago when the rest of us did?
The pool at BA probably has between 100-200 people swimming in it, some of which for 2 years all trying to better their careers with improved T&C’s and worklife etc. Why you imply there should be a god given right to jump from one of the best employers to the next and to do it sneakily via a back door, I don’t understand. I’m sure the monarch pilots could have applied the last time BA’s recruitment was open- and while you wish they had recognised your colleagues experience immediately after Monarch went under, at least they can all apply now and leapfrog the unrated souls in their pool.
A word of advice for the BA interview to your friends- think carefully about how you’ll answer BA’s first question to you, ‘So why do you want to join BA?’