There's a general and larger question than just "weed for autists" that needs to be discussed - and it touches on large amounts of the population and "freedoms".
We've seen from the gambling legalization, drug legalization, and even things like loot boxes, etc, that there is a subset of the population who just cannot handle these things at a level most people would consider "responsible". We last had this nation-wide conversation around drinking, and prohibition had its problems, but we're going to have to support this group somehow, or let them be exploited by advanced companies as if they're subhuman.
It's a good way to frame the discussion, with the caveat that for some things that subset is 5% of the population, and for other things that subset is 95%.
Is there a threshold? Can we define a principle that covers the entire range?
It seems clear that in the ideal scenario, people's freedoms should not be curtailed merely because there exist other people who would do unproductive things with that freedom. And on the other hand it seems clear that "freedom" to engage or not engage with deliberately targeted highly addictive things is not meaningful, and "individual responsibility" as an organizing principle of society only takes you so far.
Unfortunately, you'll never get it to where people aren't going to become addicts to these things. You can only reduce harms by regulation and social support.
Gambling is a decent example of where we've lost touch with this in the last decade. In my state, it used to be that if you wanted to play games of pure chance, you had to go to a physical casino, present an ID, and be subject to the rules and regulations of the state which were enforced by actual state LEOs who were always on-premises. If you wanted to, you could sign an affidavit that would ban you from the casino floor on the risk of a misdemeanor trespassing charge.
Now, you can open an app on your phone and place sports bets. There's no harm reduction at all. The apps are designed to be as addictive as possible, minors can sign in under their adult guardians' accounts, and there's no way to ban yourself from the apps. It's destroying people's finances from a very young age.
That's what happens when you don't regulate on the rationale that regulations keep line from going up.
12 Step recovery and adjacent programs fill this niche quite well, and new communities are popping up all the time to deal with more modern addictions, like internet/technology addiction.
I'm sober and have been in that world for several years now, and the most important (and hardest) part of getting sober was accepting that I had a problem and needed help. Macro policy decisions can help with access to an extent, but addicts fundamentally cannot make better decisions for themselves until they first realize they have a problem. And as prohibition taught us, once the demand is there, it can't just be regulated away.
Prohibition has its problems is a big understatement.
After almost 40 years of war on drugs the problem with hard drugs is bigger than ever in the US (and other places). Meanwhile countries that have a more relaxed approach are doing much better.
I'm not saying legalize everything always but prohibition also ain't it.