iHerb have had the system in place for some time that prevents you from purchasing certain items if you live in a certain country. I hit against it a year and a half ago when trying to ship to Japan. I've hit against it several times since moving back to Australia. The thing is, they need to actually be aware that the item itself cannot be shipped to your country before they can flag it as such. I think whenever they get reports from customers saying "customs refused to let this item through to me" they will flag it that way -- but if customers don't tell them, they won't know. That's probably why the item is now flagged that way, because they were informed and wanted to stop it happening again. And that's probably why you can find spotty management in the system. For example, I found a regular item that couldn't be shipped to Australia, but the same product from the same company but with lavender scent could. Someone got a report about one product, but overlooked the others. Things happen. People are human.
I find that iHerb provide a huge amount of information about shipping problems and possible restrictions and the like for the country I'm living in whenever I'm making a purchase, including a lot of information that I don't find available at other similar companies. I appreciate this because it's often info I'm not aware of. (I can't order products with Xylitol in them to be imported to Australia? Why? I can buy it off the shelf here! Etc, etc.)
I also think it would be an impossible task for them to know the specific customs regulations of every single country that they ship to, because they ship to a huge number of countries, and customs regulations change all the time, and with no rhyme or reason. Also, from my experience (I've worked with a company that ships overseas to many, many countries) customs officials are often really, really difficult to work with, and may refuse to let something through just because they're having a bad day, and will make up reasons and lie through their teeth to customers. We had trouble more than once with customs and the postal service in Canada. And we were shipping toys. Nothing harmful there. Even if iHerb had all their customs stuff correct, items could get refused because of one crabby customs officer.
I'm not saying that this is what happened here -- I can't possibly know the truth of the situation. But I'm just saying to be aware that it's every bit as likely that Customs was lying about the situation as it is that iHerb was. Just because they're Customs doesn't make them more honest. Customs are just as happy to "pass the buck".
Anyway, I just think iHerb do the best they can, and that they're just human. I've been ordering from them for some time now and always been satisfied, and they treat me well. YMMV. If you're disappointed in them, then I suggest you look elsewhere.