Novel, but I'm not sure they have . . . standing? An available remedy? Something. Insert appropriate term of art here.
Though, if this sort of suit somehow forces the Administration to again fund USCIS above its regular, fee-driven budget (no taxpayer money currently goes toward immigration and naturalization - it's a self-sufficient agency), they go for it.
'Cause a green card would be nice. No rush or anything. Y'all just take your time, USCIS.