Take any country below the equator and chances are the US has probably used its military against it. That's not defence. You don't collaborate with that actor if you think defence is the goal.
If we set that aside as an aberration, then yes your right.
Would you have been okay with Russia going to Iraq's aid when the USA invaded the second time? You think it's fine if Russia not only fought American troops in Iraq, but bombed the USA as well? That would have been defense by your logic, since that's exactly what the USA did to Iraq in 1991.
Fascinating worldview indeed.
That never happened. The only thing that happened was SH having a talk to a US diplomat who was noncommittal because there was no official position on it yet. Because nobody expected SH to do something that stupid.
You could rephrase ALL invasions as "defense of another". For example, Putin's excuse to invade Ukraine was 'to "protect the people" of the Russian-controlled breakaway republics.'
Otherwise you're just arguing that countries can point at some random object and say "that's under my watch" and bring armies to fight for that thing. In a sane universe that's called an invasion. Whether the invasion is morally justified or not is another matter.