I don't think this is a trophy photo, I honestly believe that these are what these guys just happened to be carrying at the time the photo was taken.
Don't make to much of the fact that many are unslung. EOD guys don't do much humping, they ride everywhere. And if they are actually doing any shooting at bad guys then something has gone wrong, i.e. an ambush. Slings in vehicles get in the way more than help.
Other reasons why I'm leaning toward this being a non-trophy photo:
1. They each only have one weapon (with the exception of some sidearms). For a trophy photo they would have been displaying more.
2. Some DO have issue weapons.
3. Some have no visible weapons at all.
4. If they were wanting to show off their trophies, we would not be having such a hard time IDing them.
5. sturmruger's comment regarding the lack of uniformality in their uniforms would suggest a command structure that would also allow nonuniform weapons use as well.
6. As a former company commander, I'm not sure whether I would have allowed this (depends on the circumstances, shortages, how the battalion commander might have felt, etc.), but I can say for certain that weapons locked up in the arms room are less likely to be lost/stolen then once being used and carried every day. Commanders are accountable for the issue weapons, not the trophies.
Just my $.02. YMMV
Michael