I'm just gonna flat out say, I think Kenji was a creep. Not, like, to unforgivable levels, but I feel like it was made pretty clear from the very start that Saho wasn't taking his approaches seriously, and yet he (and, honestly, everyone else, even Tamaki) basically saw it as guaranteed that Saho would eventually say yes to him. Even her gossipy coworkers just saw it as this cute love story, rather than paying attention to what Saho actually said or felt. It was very uncomfortable to me, in how it seemed to illustrate the "dogged nice guy" trope where a man is seen as entitled to a woman simply because A) she hasn't flatly said no, and B) because he's put a lot of time into pursuing her...and frequently the former will slide. He really stunk of cishet male privilege.
Like, Saho was nice to him - because she's nice to everyone. And the only one she showed any special interested or attention toward was Tamaki. Whether Saho is bi or a lesbian, I think the subtext is that she was attracted to Tamaki from the very start, even if she didn't realize it, while she never was interested in Kenji beyond him being a "friendly" regular customer. While it's easy to say, "Well, she should have clearly shut him down," it's also implied that she's got some self-image issues that would lead her to assume any flirting is non-serious or that she shouldn't assume he meant it.
He's not evil, but that's sort of the problem. His behavior is so normalized that nobody even bats an eye at it, despite it actually being kind of creepy and troubling. I'm glad Tamaki was there, not just because she had a chance to confess as well, but because I would worry that, absent her giving Saho motivation, Saho might have been pressured into doing something she clearly didn't want just to get out of that moment. Or Kenji might not have been even as "graceful" a loser as he was. Did he really seem like the type to take "no" for answer? I'd see him as the sort who just assumes that means he has to try harder.
on another note, score one for good representation of different body types in a yuri manga! another banger from sal jiang!