I think the whole point is they couldn't maintain altitude on the remaining 2 engines, let alone gain any. Loss of a flap would probably trigger a flap freeze if they tried to raise them so they were likely very draggy too, and whether the u/c (some or all of it) responded to an up selection after all that abuse being dragged through a building or a tree we don't know.
I disagree that "any brick wall would have taken the whole wing off". The strike was a glancing blow on the underside of the wing at almost its thickest and thus strongest point. This thing was Boeing Built remember, I very much doubt a hut of that size would take the wing right off. I'm also beginning to wonder if it wasn't made of timber and not brick. The construction doesn't look right for brick in the video above.