This is clearly marked as speculation in both the title and the body of the article. It cites a fact from a totally non-questionable source (Arrington himself

This is clearly marked as speculation in both the title and the body of the article. It cites a fact from a totally non-questionable source (Arrington himself says he's moving) and then explores the potential implications, based on tax law and market analysis. If we're allowed to speculate on HN, why can't SFGate speculate as well?