It's more than punishing any one company.
The US has very strict regulations on what technology can be exported, and whenever any tech trade is approved it ALWAYS depends on the practices of the other company. So if (for example) US companies have tech transfer waivers that let them do business with Sukhoi, and then Sukhoi turns around and sells stuff to Iran that US companies are not allowed to sell, then the US has every right to pull the plug on US trade with Sukhoi because it becomes a conduit for tech transfer from the US to Iran through the third party.
The US gets burned on this over and over and over again, so it's nice to see someone get the guts to finally enforce the rules. They all hate us anyhow, so we have very little to lose by protecting our interests. We can win the popularity war through complacency and appeasement, but that way lies ruin and loss (evidence - N. Korea nukes). It's hard to blame the President when he makes the decision that he's not going to go down in history as the President who, through a policy of appeasement, pretty much gave nukes to another nation for free (yea, a Clinton reference).
Although sometimes the enforcement seems selective, it really does make sense if you get past the idiotic and ignorant way the news media reports these things.
