After discussing the ep with friends last night, I've changed my mind and no longer think it was suicide. Like my sister said; he was begging for his life and was so relieved when Jin didn't shoot him, it didn't make since to comit suicide five minutes later.
Like someone said earlier; someone else was in the room to make sure Jin completed the job he was sent to do.
My memory is a bit fuzzy, but in a previous Jin/Sun episode, wasn't the the reason they were on the plane in the first place was because they were running away? Maybe Jin knew that Sun's father knew that he hadn't killed Jae and would be out for revenge.
Too early in the morning to try to think this out.
