In Iraq, Poles did not defend the US.
Bush and Rumsfeld claimed otherwise:
en.wikipedia.org/wiki/Bush_Doctrine"a strategy of 'preemptive strikes' as a defense against an immediate or perceived future threat to the security of the United States."
So, in the mind of the American president Poland came in the defense of the United States.
That was your question and you got your answer - whether Poland would immediately run to America's defense. It already did. Twice.
The question wasn't about what was the military significance of the Polish involvement, whether it was right or wrong, moral or not. Poland was called upon as an ally and it answered the call. It means that it can answer it again, especially if the US is in an actual, real danger in the future.
Btw, those a few thousands Polish soldiers in Iraq and Afghanistan meant less American boots on the ground and that's always something for the families that stay behind in the US, I imagine.
As for the number of Polish soldiers who died in Iraq (22), who were wounded (150) and those who died in Afghanistan (44) - what's your point? You'd rather more were killed? In the battle of Mogadishu in 1993 ("Black Hawk Down" film) "only" 18 American soldiers lost their lives and apparently from 800 to 1000 Somali insurgents were killed and probably 4000 were wounded.