Without having any direct connection to the bb'ing.com case, as I don't happen to have any personal connections there. I'm speaking only very much in general with regards to the nutritional supplement industry and this matter:
It's a real mess. First, even outside of prohormones/prosteroids, there's long been a gray area, ranging all the way from only a "eggshell white" to pretty dark grey, as to what exactly can be in a nutritional supplement. The highest standard has, since DSHEA, always been that a compound had to be naturally occuring, present in the food supply in items ordinarily consumed as food, and esters of these were permissible as that's long been accepted.
But there are some synthetics that have been around a long time and no one cares about. They're very similar to the natural product but are in fact modified, generally either to enhance stability or to improve solubility but not to change function in the body, defeat enzymes, etc.
So that's the "eggshell white" area, with regard to nutritional supplements in general.
Personally I'd put the 17-alkylated steroids in the very dark grey area even if they weren't anabolic steroids, on account of that modification adding liver toxicity and changing metabolism within the body, rather than simply adding stability or improving solubility. But that's personal evaluation, and is subject to personal opinion.
When the Controlled Substances Act of whatever year (somewhere around 2003?) was passed, my reading of it was very plainly that compounds chemically and pharmacologically related to testosterone were banned.
I can tell you however that advice was put out, from at least one source that a person could very legimately have considered authoritative, that if a compound was not specifically listed in the Act, then its sale or possession couldn't be prosecuted.
There is shady stuff that goes on in some places. Again, no reference to bb'ing.com is intended as I have no connection and no real knowledge about what they specifically do.
However, it's fair to say that while the compounds in question clearly never were naturally occurring, there was advice out there that made it, at the least, not insane and not deliberately criminal for companies to be selling them. From the standpoint of trying to read the law according to intent and what it seems plainly to be saying though, these compounds never were good. But there was different advice out there.
Btw, I also don't mean this as criticizing any particular source of information. In fact I am certain that the advice was with the best of intent, was according to knowledge of what the government was doing at the time and what at the time could be done without then attracting problems, and had a whole lot more background behind it than any amateur legal opinions of mine! It is just that things didn't go as expected for the sellers of these synthetic anabolic steroids, which is what what they are really.
Perhaps much of the reason we are seeing fines rather than lengthy imprisonment is that it's likely that the CEO's and other persons involved were able to show that they did seek sound and competent advice, and followed it. That tends to do a lot towards the government choosing fines instead of prison terms.