Two questions:

Is it a pillow fort?

Where is JD Vance in this scenario?

a) can forts be molested b) does holding something down meaning it’s being molested?

I don't know, but that's what I think off when someone says "hold down the fort".

think paper weights c)

And if the expression was "hold down the bouncy castle" that would make a lot more sense. Not as an expression .. but on a windy day at least.