Plate mechanics with runners on base

[WestMichiganBlue]

A disagreement in our FED training class tonight and I would like your opinion.

Runners at 1B and 2B, no outs, ball hit on infield. Play will be at 2B or 1B. BU has first throw, PU has lead runner to 3rd. Instructor wanted PU to go onto infield up 1B line to back up BU on play at 1B (swipe tag, pulled foot, etc.), then move across diamond to cover possible play at 3B.

I maintain that PU should not be on infield because of the possiblity of a play at home (throw would be coming from fair territory). I believe PU should move up 3B line a short distance in foul territory to where he still has a good angle to 1B. If a throw goes to 3B he can cross over into fair territory to make that call, and will be in correct position (infield side) to take the runner home should the ball get past F5.

If there is no play at 3B he can drift back to home to be in the correct position to take a play there with the ball coming from fair territory.

What say you?
WMB