I hate the current interference rule. The maximum penalty for this situation is a curtesy violation. And that is only if player A refuses to move his bag if someone else asks him to. .
Also, the current wording of the rules basically allows you to interfere with your own disc without penalty. There is only a penalty for interfering with other players disc. To administer a penalty for interfering with your own disc, you have to use the rule of fairness and find the most similar rule, if that is how you want to interpret the rule book.
While I can concur with this legalistic interpretation, all of that is negated if someone simply says, "hey move your stuff in case a disc comes back down towards you." If he doesn't then a courtesy violation will suffice for me. BEFORE he putts he doesn't know if the disc will come back AND he then has to adhere to my requests to move his stuff from here on out or risk a penalty stroke. Fair warning is fair warning ... even the rules don't require a penalty everytime. SO it's up to someone in the group to note that. I do every time I am on a runaway green.