I'm occasionally on that forum too - we're slowly resurrecting a shed & cage structure we found under some blackberries (
) with the intent to raise some tasty, tasty ducks in the future. Anyway, those guys *totally* know their stuff so if someone has a good reason for the sheoak/poison thang, I'd believe them. But then again, I was under the impression that sheoak needles just smothered other baby plants or increased the acidity of the soil or something rather than actually poisoned things so maybe it's an urban myth situation...
Sorry that's actually no help at all, eh?!