I like how Senri really put into perspective how the typical indecisive harem protagonist who refuses to make any decision (even one where he chooses all of them) on his harem is really making a scumbag playboy move. It ends up stringing all the girls along so they can fawn on him for longer and in increasingly desperate ways because of competition (even if it wasn't intentional on the part of the protag).
Case in point, Liara pulled out all the stops for Kazuki, including sex(!) and she still lost anyway. If Kazuki made his choice much earlier he wouldn't have gotten to have "free sex" with Liara because then she wouldn't have needed to keep escalating her seduction, just for that chance to win him over. He benefited at her expense just by not making any decision: sex with someone she loves but who does not love her back just ends up becoming a painful memory for her. It was also not his first time so there's the possibility he already took advantage of yet another girl before Liara made her desperate last stand.
One could make the argument that Liara could have just given up, but it's her who's chained down by emotions and not him. It's easier for him to reject her early than for her to give up, given he didn't seem to be as strongly in love with her than she was with him. In other words, she needed him more than he needed her, so he ended up taking advantage of that power dynamic.
Kazuki looked like he was being nice not making a decision so the girls wouldn't get hurt, but the ones not chosen all end up getting hurt in the end anyway, so in the long run it really was a scumbag move. He became a playboy in practice (even if he didn't intend to, but we don't know that). A good guy would've just rejected her long before she ended up making more bad memories for herself.
