Seems comiket dislikes peanuts...

Nah, it's just really heavy competition for space there. Sometimes you get accepted, sometimes you don't. Holding a booth in the previous Comiket helps, but if you don't apply in time or don't have anything new to offer, you lose your spot, I imagine.

"You were defeated it" sounds unnecessarily harsh.

The more fluent phrasing would be "We regret to inform you that it was not accepted." ("It" being the application, of course.)

Where is the artist from?

I like this artist, is light and nostalgic.

Really, it's sad but not the end, i wish the best to Chamupei.

He's been at Comiket before though, it's kinda weird that they wouldn't let him come back.

KiTA said:
He's been at Comiket before though, it's kinda weird that they wouldn't let him come back.

There'll be other conventions; this is Touhou we're talking about here, there's always a Reiteisai around the corner.

He was there last Reitaisai selling 2 books. What is actually the criteria for joining Comiket? Especially when it is so huge and space is probably limited?

There's also a lottery system. Maybe he had bad luck.