Discarding Outlaw to avoid 'Price On Yer Head' ability

[Elasto]

Player A is an outlaw and fighting a monster with death bad stuff and he is losing, he also has Patent Medicine which remove death from the bad stuff.
Player B has Medicine Show and he said that if player A fail to run away and use Patent Medicine, then he will use the Medicine Show to cancel it.

Player A roll a die and fail to run away and then he discard the outlaw (to avoid the Price On Yer Head ability, hoping Player B will no longer want to kill him) and after that use the Patent Medicine. Player B used Medicine Show like planned and Player A died.

But is it legal to discard the Outlaw after the roll?
I think that he should have discarded the outlaw before the run away roll for it to work.

On another note: Can a halfling or knome from the Older version (where they still had the -1 to run away) discard the race card after a roll of 5 and make it a successful run away?

Thanks!