Aberforth felt that Albert had set him up.
At the rally, that guy had sworn that once the Acromantulas left the Forbidden Forest and tried to enter Hogwarts, the threat they posed would drop dramatically. Yet he seemed to have "forgotten" to tell him that the people fighting alongside him would be a bunch of rookies.
This was practically setting people up to die without consequences! When Aberforth had led people in attacking Hogsmeade before, it had not been like this. Back then, his companions had been well-trained, rich in combat experience, and possessed incredibly strong mental fortitude. Unlike this lot he had been given to lead—just encountering the advance Dementors had left them trembling in terror.
What kind of people were these? Had every single rookie been stuffed into his unit?
"Can such a terrible team really stop those car-sized spiders?"
Aberforth quickly realized just how foolish that thought was.
After all, Acromantulas were classified as XXXXX creatures. The pressure of facing such monsters head-on was not something ordinary wizards could easily endure. The idiots whose wills were even slightly lacking had not turned and fled at the sight of the Acromantulas only because the earlier Dementor ambush had left their bodies weak and limp, making them unable to run at all.
Aberforth truly did not understand what Albert had hoped to accomplish by placing those people in his unit.
Honestly, even using them as cannon fodder would have been better than the effect they had on the entire team's morale.
If Albert had not remembered to leave him a few fairly reliable companions, Aberforth suspected that the moment those car-sized Acromantulas attacked their defenses, the taut strings in everyone's minds would snap.
Fortunately, most members of Dumbledore's Army were fairly brave, and Professor Albert's Spider Repelling Spell worked