Another Interference Question

[JefferMC]

R1 on 2B. B2 hits a slow roller straight to F6. F6 backs in to R1's path resulting in "slight"/incidental contact. R1 crosses plate (apparently scoring), B2 is safe at first. Defense then appeals the contact and is granted an out on interference on the contact.

In a subsequent game. R1 on 1B. F4 charges ball (from behind baseline to in front of baseline) and fields it. Observer tells me that F4 should have stopped in the baseline to draw interference. I relate situation from previous game and he says players are coached to do this.

Is this the way you think interference is to be treated?