As of build 1286, animator updates no longer propagate to "Allow Grabbing" property.
Replicated through:
avtr_440de033-9a75-4464-b6fb-fe3df677db93 under /ratshot_jug/ratshot_Skin/tag_origin/j_mainroot/j_COCK, last two layers in FX controller. QM > Funnies > Disable Crotch Plate Grabbing
Under normal circumstances upon lifting the crotch plate's bone (j_COCK) enough to reach 0.65 in reported angle, you would hear a demoman's "ka-boom" voice clip play. As expected, when the crotch plate grabbing is disabled, one can't grab the bone and can't trigger the voice clip playback.
Presently, one can't grab the bone regardless of its configuration.
This potentially affects other properties as well; haven't checked.