As far as I can tell nobody is stopping you from doing this. Just as you can legally hack iPhones if you figure out how, so can you hack your Tesla. The only slightly illegal thing might be the anti-circumvention provision of the DMCA, but you'd have to take that up with Howard Coble and the members of the 105th congress.

My comment is reasoning for why Tesla has a stake in protecting their reputation; if you don't like it, please don't support their practices by buying their cars.