[the_third_wave]

The solution there is to set aside a few less-used fingers which, when applied to the scanner in sequence, tell it to perform a secure wipe. I'm left-handed so I use a few fingers on my right hand plus my left little finger for access, this leaves enough fingers for a fingerprint-directed wipe command:

   left index followed by
   left ring followed by
   left middle => Wipe

There is bound to be an app or option in some AOSP-derived distribution for that, if not you got the idea here.

[Gasp0de]

You will almost always use one or two fingers to unlock your phone due to the fingerprint readers position and the police might be intelligent enough to ask you to put that exact finger on.