I think we're jumping to conclusions about Diane going in. She was in Renton's vision, yes, but so was just about everything else. Hell, those three girls in this eps were in it as part of his class before they turned into whatever. Important things to Renton were in there, along with a lot of messed up stuff (that came from Anemone).

Renton's sister is pretty important to him, its no surprise she would show up.

Also, the members of the Gekko-Go do get emotional about Diane. Holland gets really weird when he starts thinking about her, and Talho gets really angry about her, and when Holland is thinking about her. If something happened, they'd show it on their faces.

It doesn't even matter that they were special ops. Holland loses his temper ALL the time. Talho gets really pissed off at the dumb shit Renton does, and she gets infuriated at Holland too. Hell, Gekko State wouldn't even have existed if it wasn't for Eureka and Holland getting emotional and going AWOL in that city.