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.