The important part is whether or not an offside player has prevented a tackle. I'm just saying I thought the defender was too committed to the inside centre to change his mind and tackle BOD instead. So while the guy was technically offside, the move was timed so well it didn't have an effect so play on was fair enough.
I agree with you that the issue is about whether or not the decoy runner has prevented the defender from making a tackle and in this instance I certainly think he has. If there was no decoy runner at all then I think that defender was close enough to BOD to make an attempt at a tackle.
The decoy runner has prevented the defender from running in a straight line at where BOD was running.