I don't know if you're trying to be sarcastic, but I'll assume good faith - the goal of US sanctions is to destroy the Russian economy as much as possible to weaken Russia. Russian citizens coming to the US is good for the goal of weakening the Russian economy.
Russian spooks would find a way into the US no matter what.
If I visit Iran, I can not go to USA.
I think US should apply the same rules, and cleanse themselves from all Russian influence. All Russian developers, tech, companies...
If you go to Iran, you certainly can go to the USA after. You just need to ask for a new passport, and the US will never know what happened.
These sanctions aren't about influence. It's really just about trying to weaken Russian economically. The US government seems to think that Russian and Chinese influence is not that big of a problem, and they are probably right.
Russian spooks would find a way into the US no matter what.