power store does not have a setting to turn ssl on or off.
the code block you reference in your first post is used to determine whether the https address can be accessed or not.
if you access the checkout page using the address;
that code block tests the address:
if it can successfully access the https address, it will redirect to the https address. If it is not redirecting, then the test for the https address failed because SSL is turned of at that address.