Following up on this for anyone else. If you monitor a stored procedure via SQL Agent, you're only seeing the result after it's scheduled to run and the results only persist at runtime, whereas if you have LogicMonitor run the stored procedure, you can schedule the frequency in the DataSource and the results persist in LogicMonitor. I found this gives you more reliable alerting and monitoring.
To accomplish this I leveraged the JBDC data source; constructed the JBDC URL, ensured the LogicMonitor service account has sufficient permissions (it is used by default) and then modified the SQL query to output a number. Then configured the Datapoint to guage the resulting number and alert when it that value (corresponding to a column in the query) equalled X.