It's difficult to determine, at the LOS, whether or not the hold will affect the play or not. If a WR is held a the LOS, do you not drop your flag or do you to wait and see how the play develops and then if you feel it affected the play, come back and throw it?
I think it'll look terrible if you waited for the WR, who was held at the LOS, to get 20 yrds downfield to then determine that he may have had a chance to make a play on the ball if he had not been held and then run back up and chunk a flag.
If do enforce the penalty, on this play in question, it would be from the end of run. 1 and 10 at the A40.