I'd be wary of trying this as it reeks of "one neat trick" thinking applied to law based on a small technicality where law is often subject to the spirit instead of strictly hewing to the most favorable interpretation the exact wording for the citizen. The warrant can just state you're required to unlock the system not simply "make your fingers available".

It's fun to try to find places where the rules seem to leave holes but it's important to remember the courts don't have to hew precisely to how you read the law. I see that a lot on tech centric boards where the law is treated like it's strictly, precisely, and impartially interpreted down to the exact words (though often not using the legal meaning of words which have decades of caselaw and interpretation informing their legal meaning).