I didn't imply that Israel/US was subject to Iranian jurisdiction (not least because countries are sovereign). I wrote that it was probably legal (at least within specific boundaries) for the Israeli/US governments to approve such actions on foreign soil, which are after all one of the raison d'etre of the CIA and Mossad. But of course the operatives in Iran did commit murder under Iranian law and they were subject to that jurisdiction.

It's always a question of perspective.

Regarding your second point, there is obviously a part of intimidation in doing something like that. It's even mentioned explicitly off the record in the article:

"But some American officials argued that the death of Mr. Fakhrizadeh, the latest in a string of such mysterious killings of Iran’s top nuclear scientists, would send a chilling message to the country’s other top scientists working on that program: If we can get him, we can get you, too."

'Terrorism' is a term always used against others, the bad guys. We are the good guys we never do that. Some people have bought this line so much that it's difficult to accept that everyone does terrorism to a varying degree, at least certainly from the perspective of those on the receiving end.