When Brock says "we'll get to the bottom of this"...Brock has Dana/The Mob/Mr.Mcmahon/HHH all in his corner to help pay off whoever it is they need to pay off. If it means Brock has to fly to the Mirage hotel and cross the imaginary line, than the cock tattoo on his chest tells us that will be no problem whatsoever...
It's going to be as simple as this:
Brock is in touch with one of the standard athlete lawyers.
Brock takes over the counter, approved supplements.
One of them "happen" to have tested positive over the last few years for contamination.
Lawyer brings attention to the problem with chain of custody in the test.
Enough reasonable doubt that the case is dropped and Brock moves on.
Everyone presumes he would never lie and they forget all of this within 3-4 months.