As far as I can recall Bladorthin occurs only in 'The Hobbit'. We cannot, therefore place too much weight on his importance (or even his existence) in relation to LotR. Bladorthin is like the stone giants hurling boulders in the passes of the Misty Mountains...an anomaly with no real place in the mythos that grew up around 'The Lord of the Rings' and 'The Silmarillion'. It is always fun to try and find a place for these misfits, but in the final analysis they are just that. Misfits.