My interpretation of what's said in the article is that he was going to call it off because it was getting late and Filin hadn't come out yet. Just as he was going to call it off, Filin appeared, and so, instead of calling it off, he told Zarutsky that Filin just came out of the theater and was probably going to drive home. So I don't see much contradiction.
I misunderstood -- I thought he meant he was calling to call off the attack altogether, not to give up for the night. That, too, contradicts the earlier statement attributed to him that when the beating didn't happen right away he forgot, and confirms one of the early reports that he confirmed when Filin was heading home.
If a fellow dancer witnessed the stakeout, even if had no idea what Dmitrichenko was planning, he would have overheard Dmitrichenko's end of the conversation and was a witness to his friend's plotting. It would also counter the assertions that there was no way Dmitrichenko could be involved. No wonder he was a reluctant witness and resigned.