Hmmm. No matter the exact wording of the rule, I disagree with this call because the runner had a clear path to the base. Regarding the rule requiring the batter-runner to be on the foul side of the foul line when approaching first base, I think it needs to be clarified. I also think it should be strengthened, with every batter-runner who is in fair territory past a certain point being called out whether interfering with the fielders or not. This will require some adjustment on the part of baserunners but, as with the rule change put into use around takeout slides at second base, if the rule is clear it shouldn't be difficult. BTW, on a slight tangent, I have sometimes heard people use the term obstruction instead of interference when a runner interferes with a fielder making a play on the ball. The correct terminology should be used.