Like others have said, attempting to force abstinence will certainly backfire. The solution is to teach him to use responsibly.
None of the drugs you've listed are particularly harmful, as in, they don't kill brain cells. If he really does know "too much" about drugs then his behavior so far suggests he might know which ones cause permanent harm, and to avoid them.
I suspect undiagnosed autism as well, perhaps some savantism, which can be used to an advantage. With the availability of information on the Internet, he may be as well-educated on drugs as a first-year college student. I'm speculating, though, as I interpret "knowing too much" as being "that guy" whereas some parents may thing any knowledge of drugs is "too much".
Regardless, the interest is certainly there. Interest and curiosity are the driving factors behind learning.
You may be able to steer him toward a career in medicine, pharmacy, chemistry, or something related.
If you have money to spare, get him this book. It's a second-year college level neuroscience textbook, often described as the "Brain Bible". While it doesn't cover much directly related to drugs, it does cover the workings of the brain, which is what drugs affect.
A textbook on pharmacology is also a good idea, though I have no good suggestions for that one.
For less technical reading:
PHIKAL: A Chemical Love Story by Alexander Shulgin is a classic on drugs and drug chemistry. Don't worry about the recipes in the back; the materials required as excessively hard to get.
The Doors of Perception by Aldous Huxley is another classic. PDFs are widely available of either.
Speaking of, here's a PDF of the DSM-5, the manual for mental disorders. As often said in engineering: read the fucking manual.
He likely knows about Erowid and PsychonautWiki; but if he doesn't, then he should.
But, yeah, don't fight this. Guide it into something more productive. Drugs are a technology. Drug science is science. This opportunity comes only once in a lifetime.
Speaking from experience, nothing causes mental trauma in a teenager more than having your interests shat upon by your parents. They can either feed the flames of passion, or drive their kid into further despair.