We know that Blizzard's spell scripts sometimes have very weird and unexpected side effects and properties (a fact that scares me from time to time). See the current two-piece elemental bug, where apparently Elemental Mastery is put on a seven day cooldown if the set bonus triggers, but only if used in a random dungeon/heroic (and there may still be other factors involved).
My mind simply cannot begin to comprehend how you could construct such a bug even on purpose. I have absolute no problem believing that certain spells causing mobs to crit more is a side-effect of their scripts, intended or unintended.
For what it's worth, our warrior got hit (non-blocked) by Stinky after using Shield Block (and again during a Mortal Wound application), which definitely seems to indicate that the spell is futzing around with the combat table.