Even with just Brawn 5 and no skill against 5 purple, that freak of nature manages to hit point blank with a grenade ~50% of the time. Most of the time with threat but still, roughly every second throw hits. Throwing in 2 Setbacks for whatever and upgrading it once is easily offset by aiming (+1 boost) and 2-3 skill ranks as this will achieve ~50% again - that's ridiculous.
I can accept that this would sound fun, but for me, that is something a destiny point should be required and not made something basic you can do every turn every combat.
I think destiny points are made for those situations where you try something ridiculous but fun.