I currently think that Seism is easily fine without the massive stalling capabilities.
Against any deck that is completely dependent on pillars/pends for their quanta, and without the ability to aptly protect them, Seism will either force them to make their decks much less effective and then run over them, or just take away all their quanta while they try to rush.
Added with stalling capabilites, Seism can now stall opponents where his EQ would become less effective. Not even decks with eternity would be a 100% win against a deckout deck(See: EQ, Rewind, BB, Sundial, SS, Diamond Shield,Warden,Pulvy).
Having the ability to rush, the ability to QC,PC,CC, and hand control, and now stalling capacities, I think Seism is now way too strong.