So they asked Charlie Brown for his opinion specifically to go against it? That's not very friendly. The wide smile on Schroeder's face doesn't seem to bear much malice; they don't appear to be intending to pass judgement on Charlie Brown with their action. It's just the way they decided to pick a color.
After a few strips that appeared to fairly solidly clinch Snoopy's owner as Charlie Brown, this one throws the question back up in the air a bit. Why would they be painting Snoopy's house if he were exclusively CB's? Wouldn't they grant his opinion a bit more weight in that situation?
Chagrimace!