I want to talk for a moment about the fact that 911 hasn’t forced a particular label onto Buck since that kiss. Of the 3 characters who know (Tommy, Maddie, & Eddie), they have all spoken to Buck where he is at, which is just that he now likes and wants to date a guy. Buck hasn’t defined his sexuality in general, he is just acknowledging his attraction to Tommy (and that he checks out cute man butts).
The only ‘label’ Buck used in 7x05 is as Ally, which as Maddie points out, probably isn’t totally accurate, but she doesn’t force the issue because that isn’t the point of the discussion nor Buck’s confusion. Buck needs Maddie to point out that he still is processing this shift in understanding himself, and just because he was an Ally who did the bare minimum during Pride month, doesn’t mean he isn’t going to need time to be able to be honest with those closest to him.
And the conversation with Eddie is about Buck letting go of that fear, of allowing himself to risk potentially losing the people (because if he loses Eddie he loses Christopher) who mean the most to him outside Maddie by clarifying that his dinner with Tommy wasn’t friends hanging out. And although Eddie questions and labels Tommy as Gay, he doesn’t label Buck at all. And this makes sense. Eddie knows of Tommy only through the emergencies they have worked on together, as well as hanging out doing masculine things. They probably haven’t discussed dating history or attraction, and aren’t going out looking for hookups together, so Tommy’s sexual leanings probably haven’t come up. Now that he knows Tommy and Buck were on a date, without any other info, gay seems to be a perfectly valid label for Eddie to apply to Tommy in that moment.
But Eddie knows Buck, and has done for years. He knows Buck’s dating history, which has been solely women. It’s possible he has also noticed Buck checking out men, but not acting on it beyond that. And Eddie also knows Buck’s kindness, and his insecurities, and fears of being rejected and left behind. He knows that what Buck needs in that moment isn’t judgment, or to be questioned. Buck needs acceptance and reassurance that him dating a man, regardless of labels, doesn’t alter their friendship. And Eddie gives him what he needs.
Buck can take his time to find an identity, a label that works for him, without it detracting from the feelings he has for Tommy. Or choose not to label himself at all because he isn’t looking for a community or trying to put himself in a box for other people to judge whether they are safe to interact with. Because at the end of the day, the relationships and feelings are what should matter, not how one labels themselves if the choose.