According to reports, he did so solely because of he didn't get a vanity van of his own.
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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.
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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.