I like to think that Picard's irumodic syndrome gave him a disability immunity to forced Vulcan mind melds. That and his mind meld with Sarek might make it very difficult if not impossible for Oh to brainwash him.
If the mindmeld failed on Jurati, Oh could just kill her and few people would care. If the mindmeld failed on Picard, he'd report that Oh just tried to mind attack him and she'd have to kill him, at which point she'd have the likes of Riker, Worf, and half-Betazoid Troi moving mountains to find out how Picard died (or maybe not, the Voyager crew suddenly couldn't be bothered getting justice for Icheb other than Seven).