Here's an idea:

How about during the event when they show the matchup graphics (age, country, record, weight, etc) they add a note at the bottom of it *this fighter has passed optional VADA testing for this fight *this fighter declined optional VADA testing for this fight

And a new rule:
Fighters will not be allowed to discuss drug testing during training camp, but instead, will have to answer to media questions AFTER the fight.

for example:
At the post fight press conference: "Hey Johnny, why did you decline VADA testing even though GSP offered to pay for it?" "Sorry guys, I thought since it was voluntary and not mandatory, it would be a distraction to my training"

So then we wouldn't have to deal with this so called media bullying before the fight