If panel with result set was hidden it should be unhidden on the next query execution.
Otherwise it is unclear whether the query has been executed or not.
For comparison, SSMS behaves this way.

See a gif: https://i.imgur.com/pN6rvXW.gif

Steps to reproduce:
- execute a query
- hide panel with result set by mouse click to its horizontal border
- execute a query again

Expected: the panel with result set is shown.
Actual: the panel with result set remains hidden.

If user executes any select-statement he usually wants to see a result set, doesn't he?
So I don't see any reason to keep this panel hidden.
This suggestion has a request-number: 143966