It's like Kyle Rayner BTFO'ing Juggernaut and some other clowns...he did it, but he couldn't do it himself, it was Iron Man's design.

Alicia doesn't have powers so her designing the mech doesn't change the fact that Sue's construct can KO Thing and Reed which is what the op asked about

Reed and Ben having the exact same durability threshold is hilarious.

Normally in these situations it's assumed it's just the force needed to take out the toughest member in the group. But it specifies a line and the Sue's mech pushes them over that line, with them visually getting hit by the same blows.

It just means she hit them hard enough to KO both without critically injuring or killing one or the other and not that they have similar durability