I noticed this as well while exploring Cav EQ. After a quick investigation...part of MODOK's Flux abilities is +25% ability accuracy. since Lock On is 100% AAR, the extra 25% ability accuracy that MODOK gains from his flux cycles will give him a chance to Auto-Block. So it's possible!
So far modok has not auto blocked me
i had a similar-ish interaction with falcon vs the debuff immune nightcrawler in 5.4.5. he evaded me despite the locked-on. he did have the node "all abilities trigger x% more often". does that translate to bonus ability accuracy as well?