i mean assuming the scout coming in to the fight just respawned and has full 125 hp, pretty sure he can come in to the fight and make it a 2v1 no matter if you crit heal him or not
but i feel like the safer bet is gonna be crit healing your scout, unless ur scout 1v1'ing the other scout has very low hp then i would heal my scout in the 1v1
but also it's not like it takes 40 secs to crit heal a scout to 185, it takes less than a second or 2, so you can literally just poke ur scout that coming in the fight with ur med beam and he'll have a respectable 160ish buff or 185 if you keep it on him for a few more miliseconds, then you can heal the scout that was in the 1v1