According to reports, he did so solely because of he didn't get a vanity van of his own.
Kapil was apparently supposed to start rehearsing with Mandira, also co-hosting CCL, by noon, but showed up a good two hours late, leaving no time for rehearsal.
Reportedly, Kapil's team made a lot of demands and after the organisers offered him an AC room, he plain refused. He eventually walked out, leaving no time for the organisers to recover.
According to reports, Kapil, who seems to share a great rapport with Salman Khan, was afraid his antics would upset Sallu bhai, and his brother Sohail Khan (co-owner Mumbai Heroes). And when Kapily called Sohail up, he apparently told Kapil to keep out of it.