[jsjohnst]

An alternative is to just turn the device off before you walk up to a potential issue. That way you're assured that the TouchID won't be accepted (last thing you'd want is to learn it only registered X presses rather than the Y required to disable). In the event you are caught off-guard, disabling TouchID is as simple as just holding in the power button until the screen goes black. If you practice this a few times, you could accomplish this even in a stressful situation.