There's no logical explanation, except that he's just an idiot
This is just my grasp on how much substitute hates eungyeom so I think that he thought that eungyeom life kinda disordered in subtitute eyes with mockingly like 'ugh it obvious he's that kind of guy of course he had a kid out of marriage (degrading tone)'
He says it's understandable for 2 reasons:
1) that eun-Gyeom has a kid before marriage 2) that his kid has no manners ( cuz she started running and fell on him) becuz her father is eun-Gyeom
(╯°Д °)╯╧╧
i don’t get why the loser said it’s understandable he had a kid, when he looked at eungyeom and eunha. Can anyone bring explain what he meant by that? Haha