Well Bonnar was suspended for 9 months for steroid use after his 2nd fight with Forrest, not all suspensions are the same. There are other factors involved in that like first time offense, where the fight took place as well as other factors.
But yes, it very much is common sense to look at Jake's situation and say it's far less likely it was weed then it was some substance being used to help add bulk. It's far less likely Jake would hide a positive weed test then it is he would hide a test about a PED or some other banned substance. It's more likely it was a pain killer then weed as well. I don't see the point in hiding a weed test when that is the best possible scenario for Jake. Why leave room for assumption if the truth is the best possible scenario in that situation? Again, common sense.
"For all we know, Jake was busted for smoking up and is too embarrassed to admit it to the world. Or maybe he believes in privacy. Either explanation is plausible, but again, entirely speculative."
Perhaps if it's weed thats why he is hiding it. It's common sense to look at both sides, not just one, which seems that you're going at. You think just because he doesn't come out and say what he took that it can't be weed, though you have no idea.