As a side note, I spoke to someone else from my board and he could imagine this situation unfolding in all three types of calls (interference, obstruction, and nothing).

He also had an interesting take on the play at first base on the slow roller with F3 straddling first base and the BR bearing down on him like a freight train. (I had this as interference.)The BR is able to over run first base and the play at first is not a force. The force play slide rule and all of its kissing cousins would not apply. The BR is restricted in his baseline in that he may only stay in the running lane, but is required to cross into fair territory to touch the base. There is literally nowhere for him to go unless he completely gives himself up or gets creative with his slide. He said that even if they two players train-wrecked, he'd call neither obstruction nor interference. It did get me thinking. Certainly an interesting situation.

I like interference there. It's sellable...unless the first baseman gets trucked...then you're going to have a mess.

The end of that rule states, 6.05k .................except that he may run outside (to the right of) the three-foot line or inside (to the left of) the foul line to avoid a fielder attempting to field a batted ball;

6.05k is for coming up the line but not at the bag. The runner must touch the bag or risk being put out on appeal or being tagged out.

Yes I agree, incidental contact can very well happen here however, if it results in the fielder not being able to field the ball, then that is interference. If it is the result of the fielder and runner doing what they are supposed to and there is incidental contact then there is nothing.