It's his right as a support player to support the play, Robinson had run him out of room on the outside, so as per standard footballing practise he came inside to continue his support, absolutely no way you can justify calling that obstruction.
Just because there are chasing defenders doesnt mean Lee has to give up his line of support, he has the same rights to be there as chasing defenders. He didnt purposefully impeded anyone, he didnt alter his line other than to come back inside when Robbo ran him out of room
by the sheer fact you think he might have impeded Nightingale says that his support was in fact required, Nightingale might have still made a play at Robinson and Lee has every right to be there on the inside to collect a pass if he did.
As it turns out Robinson was too far quick, Lee came inside to provide support and dopey old Vidot who was well behind the ball player, pushed Lee, who did not have the ball into Nightingale, who was never going to get close enough to stop the try regardless
It was a clear cut try, absolutely no doubt in it what so ever. Which is why im laughing big time at the few (and there is only a handful) of saints fans bitching about it.
It was no more an obstruction than the last RR try when Chase Stanley made a poor read