Don't like the call

[ChampaignBlue]

As I understand the rules your mechanics on this play would be to give the Delayed dead ball signal on the obstruction. When the INT occurs Dead Ball R1 is out as well as R2 if deemed an intentional act. Call over offensive coach, assuming that s/he isn't already on the way to you to complain about the obstruction and give coach the option of bases loaded or R1 out.
Had the INT occured after everyone had advanced a base then the delayed dead ball would have been removed.
I think where the INT takes precedence is when you have both occuring at the same time, for example, infielder is standing in a basepath with no immediate play and runner crashes into her, we'll be calling a dead ball and the runner out for the crash/INT and warning the infielder about the dangers of standing in basepaths. We do this for the safety of the players, fielders are watching the ball and runners are looking where they are going. Jim