Actually with crypto it won't be that easy, since one can buy/sell crypto P2P, avoiding the centralized platforms that enforce US rules.
Exactly. More importantly, once there is a critical mass in crypto, people won't have to trade in and out of it, they'll just settle up in crypto. Then there is much less need for an exchange whether p2p or centralized. This type of use if it is even real is a first step in having large amounts remain in crypto. If you buy something from ABC and they immediately trade it for fiat, what's the real point?
The more controls that are put in place the more likely it is to occur. For example, when Stripe and PayPal banned the Trump campaign in Jan 2021, the obvious answer was to just switch to crypto. Ditto for other places that are getting hit by Visa such as pornhub's parent company. Ditto for banks that are denying loans to firearms companies, gun shops or oil companies. Ditto companies that are being black listed (or grey listed) on ESG grounds. Jen Psaki said that people who spread “misinformation” “shouldn’t be banned from one platform and not others.” She wasn't talking about just social media, she was talking about the entire realm of the digital world including online payments etc too.
The end result of this will be to drive people to places that don't want to or aren't able to censor them and crypto is one place they'll end up because while it is nice to see "free speech alternatives" to some of these things, as long as they are centralized, they are subject to legal pressure.
(No comment on whether this is a good thing or not with regard to it being Iran of course).