There are many possible explanations. The old man really like Sen-chan and just used the "mistaking him for someone else" as an excuse to hide his true feelings. He was kissing that other dude for practice in order to please Sen-chan or to release pent up sexual desires. Or he really did mistake Sen-chan for the guy he really loves (the flashy guy lol). Which i doubt. I hope the author didn't fuck up this story cause I'll really cry. They would be so perfect together.
There are many possible explanations. The old man really like Sen-chan and just used the "mistaking him for someone else" as an excuse to hide his true feelings. He was kissing that other dude for practice in order to please Sen-chan or to release pent up sexual desires. Or he really did mistake Sen-chan for the guy he really loves (the flashy guy lol). Which i doubt. I hope the author didn't fuck up this story cause I'll really cry. They would be so perfect together.