Yes, the slave/peripheral can transmit data during a connection event, whenever it has a new data irrespective of the slave latency count. The slave latency is used only when the slave does not have any new data to send. It can ignore the connection events from the master for the "slave latency" counts. However, once the slave latency counts lapse, the slave has to acknowledge irrespective of whether it has new data or not. So, yes the attached use case/scenario is perfectly possible.
I hope this helps.
Meenakshi Sundaram R