and apparently Romeo tripped over a dead Unggoy and broke his ankle, so Dutch had to carry him out to escape the blast of the Knowing self-destructing. Wow! Dutch is a badass and a good friend. He's someone you can trust to carry you out of a building thats going to explode, thats gold star friend material there.
...okay....hold on I got to look up what this can thing is....oh okay that canister and foam?
its actually biomedical foam its used a form of first aid, it keeps damaged organs in place, stop bleeding and such, its used a medical option when no medical personnel are around, this stuff is used in the med kits you get in gameplay, but its only temporary up to a few hours then it breaks down. so they're not just grabbing some random thing to seal them up, they're using something that has been proven to work. though you might have a point about it not helping with a punctured lung? maybe they just filled it enough to seal up the wound and not suffocate him,? ODSTs are kind of supertrained and these are all experienced soldiers who lets be real, this is not their first rodeo, they've probably have all been trained on its use and all done this before, so perhaps they just know enough about this biofoam to use just enough and you just shouldn't try this at home.
"I wouldn't go down there even if you ordered me to"- Romeo, talking about hypothetical insubordination to his commanding officer! that immediately leads to him being a hypocrite because Buck has decided they're going down there immediately. this is why soldiers don't talk back to military superiors, it gives them ideas.