Jones is young and rich (at least by my standards) and a public figure. As far as him doing cocaine, it is what it is and the whole "I'm going to rehab!", I'm sort of on the same page as Nate Diaz... it's a publicity scam to maximize damage control.
You don't go to rehab because you tried cocaine once... you go if you have an ongoing prolonged issue with the substance abuse. Is this the case here? I'm inclined to say doubtful, but I (nor anyone else) really have enough info to go on. While his money could certainly afford him the ability to buy and snort coke at will, physically, he doesn't seem to be suffering the physical effects of a bad coke addiction. So do I think this is an attempt to publicly save face? I do.
As far as the low testing results for both fighters, I can't really make an informed opinion, but can't help but think to GSP's stance on PED's/drugs. There's too much latitude nowadays with what's tested being tested for, when, who's actually conducting it, in or out of competition, where the fight occurs (pertaining to the state and/or country), and how often the testing is being done.
Designer drugs/stimulants make it even more difficult and further complicates the process, and typically it's the upper echelon fighters that can afford them, because I'm simply assuming they would be more expensive. I don't know for sure, never used steriods/PED's etc., or am aware of the intricacies of cycling.
As far as the publicity side of things, then yes, it seems like Jones got a pass where other fighters haven't. I understand the circumstances may be different, but if this board indicates anything, it's the distinct lack of understanding when the rules apply and don't. In general, I believe most Sherdoggers are more informed than the general public and casual fans (as a whole), and if we disagree, imagine how the general public views instances such as this.
The only sure fix that I see, is mandatory testing by a third party for all fighters contracted by the UFC at specifically regulated intervals (that avoids cycling time frames), with no exceptions. Have additional random tests if any fighter is suspected of abusing the system or drugs.
If that means you want to fight in the UFC, then take the tests, don't dope or cheat, and lay off the illicit drugs. Or don't fight. Leave the choice to the fighter, and if he wants to smoke pot, blast lines, or be a part time bodybuilder, then don't fight.
It's either that or simply just let all fighters smoke, snort, and inject themselves with as much shit as humanly possible and see what happens.