You have no facts to support your claim. All you have is speculation and conjecture. I have no idea what Shields was suspended for, but I'm also not the one running about claiming, 'It's much more likely he was suspended for PEDs'. I'm not being an unbridled optimist or throwing 'common sense' out of the window, but I also tend to subscribe to this nifty little thing called evidence, which we have none of.
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.
I also tend to believe that were Jake busted for PEDs, he would have been suspended for more than 6 months. Go and take a look at comparable suspensions... 6 months for marijuana is common, whereas testing positive for banned substances often lands a fighter one year in the hotbox.
There's a novel concept... actual research!