Because the Council is obviously trying to get into the Brigade's territory, basically. It starts with the school but there's not enough to be done there so soon they will be making festivals and clubs and soon they will be trying to make even a better Tanabata event than the Brigade and thus take away interest and potential members from the Brigade.

[It's easy to see that he's just repeating what Haruhi said, not voicing his own opinion.]

Also, maybe it's because she knows you're bond to be involved, you know how she's with you.