GPS is already inaccurate enough as is when going through a wooded area or in the rain (never mind both). The kernel munging numbers for security isn't a good idea anyways, because what is "enough" data that is reasonably required to derive the keypresses? Guessing gets us nowhere because the rogue applications will only get better, not worse. So as attacks get better, my GPS tracking gets dumber? No thanks.
I would think the solution might be more along the lines of allowing an application to have exclusive access to some device (outside of kernel-level processes) when it's actively using the data.