Använd helt enkelt den här frågan:
SELECT *
FROM Guide where id NOT IN (
SELECT Guide.id
FROM Guide
INNER JOIN GuideAvailability ON Guide.id = GuideAvailability.guideId
WHERE GuideAvailability.startDate IN (1377946800)
GROUP BY GuideAvailability.guideId
HAVING COUNT(DISTINCT GuideAvailability.id) = 1
)