Scott used to pull that move all the time in the pre-Claremont days. It works for the same reason he doesn't snap his neck when firing a mega-blast - the "psionic field" his body is surrounded with seems to have 2 settings. First, ignore recoil-like effects of any kind. Second, if recoil effects are needed, it affects the body as a whole and not just part of it, like the neck.
Even when Claremont was writing Scott has used his blast to slow a fall - it's why he has brain damage from falling out of that airplane without a parachute rather than a case of unexistence.