The schedule manager can only see the content when he/she adds something to the schedule, they can then select the content from there. as far as being able to see the content tab, no. They are not allowed to see the content tab as that would give them access to meddling with the content. If you want them to, you can make them a content schedule manager who can do both.
when logged in as schedule manager, try adding something to the schedule and you will see the content you are allowed to choose from.