I am very firmly with Sitnspin here. Like I said before, it's not a date. At no point did Clinton say to Elliot, "Yes, I think I am romantically attracted to you and I would like to go on a date." He didn't say "Let's spend some time together working out my feelings for you." He said "Let's grab a beer." You know, that thing friends do sometimes. Let's hang out in a context that we have hung out in before and will likely do again because we're friends and this is normal. Clinton is acting exactly as if Elliot is his friend, which is what he is. None of this would have been any sort of problem at all if we weren't aware of Elliot's attraction to him. And it still isn't a problem. Sure, we now know that Elliot is feeling hurt. But we have a narrator's perspective. Clinton doesn't. And Clinton isn't responsible for Elliot's feelings just because he knows Elliot thinks he's cute, anyway.
Here's a life lesson that changed my life for the better. You can be attracted to your friends. That's OK. Even if they aren't attracted to you. I have a friend who if she ever said "Hey! Wanna watch 90's revival cartoons and make out?" I would jump on that chance immediately. But she won't because she isn't attracted to me. And that's fine. I don't expect her to pretend not to be attracted to other people. I don't expect her to pretend not to have a sex life that doesn't include me. I don't insist that it is "basic etiquette" to not flirt with the cute server when we go out. Do I feel a pang of jealousy sometimes? Yes. Of course I do. But that's MY issue. Not hers. My feelings are my own responsibility because I'm an adult. And you know what I don't do? Lie to her face and tell her I'm not feeling what I'm feeling and then blame her for believing me.
And this may be Clinton's answer for himself. Maybe he didn't behave like he was on a date because this didn't feel like a date to him. Maybe it didn't feel like a date because he's not actually attracted to Elliot and nothing's gonna come out of this.
Or maybe he thought they could hang out with Elliot at work as friends and see how that felt. And then he could have a few beers and have a reason to walk to his mom's place afterword instead of going home. And maybe Elliot could walk him there. Maybe he could hang around for an hour or two and he could see how it felt to hang out with Elliot in a more intimate setting. Maybe hanging out in a bar while Elliot is working won't feel like anything special, but having a few hours alone will. And if he actually planned that? Well that sure as hell wouldn't be the worst idea he's ever had. And given how quickly he invited Elliot over to his mom's the moment things started going pear shaped, it wouldn't surprise me in the slightest if he had.