posted in a wrong forum A-HAH! Caught! By self-admission! You are hereby sentenced to ten lashes with a wet noodle.

(Glad to have you. If I recall your example sentence correctly, it just didn't sound quite "right" to me; and I think it was because lest was followed by a negative. I've seen it either all, or nearly all the time, followed by a positive construct. That is, 'he studied hard lest he fail the exam', not 'he studied hard lest he wouldn't do well'.
Though that's not quite it, either: 'he studied hard lest he not pass the exam' sounds okay to my ears. )