Much worse, this will greatly improve their position with regards to wiretapping their own citizens.
Depending on who you are, Western CAs can come with some availability problems, but thanks to certificate transparency, you don't even have to trust the CA if you mostly care about security. Take a wild guess as to whether an Iranian CA will support that...
I doubt Iranians needed sanctions as an excuse to install their own CAs and require their citizens to use them. Many authoritarian regimes require their citizens to use domestically produced networking software that is different degrees of compromised.