_The following answer is based on information taken from an earlier answer written by Tokyo Nagoya, which has been deleted by the author._
As you point out, {} is a reference to the four seasons, and in the case of , has cleverly been left off (and a added). Your intuition about the part meaning that there is no autumn is correct. When you add the {} at the end you get , which is a homophone of . This is synonymous with {}, or "in business"/"open." It's a kanji pun saying that his business is open.
So we go →→→{}