Fuzzy guard just removes the extra dirt for the effort of a practice. It is fair.
With 21F start up the slide is even possible to react but it is not guaranteed of course especially during the heat of the battle (in practice room it was not that difficult).
Tbh I did not even use that kind of 50/50 of Erron. Only B2xx slide/B222 and just after many B222-s.
I rather use the cancels in 21212 and B222 to mix it up.
But yes it is silly to skip the OH/LOW mixup sometimes.