I guess Goji just didn't word the phrase that well, I think what s/he is asking is how becoming a Poison Type would give you Sheer Force flavour-wise (As an example, Flame Body if you switched the mon's type to Fire would make sense. Sheer Force and Poison don't have much of a relation)
True enough. Either way, I'm not too keen on this, IMHO, rather underwhelming STAB combo.