There are scenarios where disabling and enabling of the Pass and Fail buttons could provide additional visual feedback.

For example, the test could determine whether the tester has performed the required actions, only after this the buttons are enabled; the buttons are disabled when the UI starts.

A scenario from JDK-8316211 code review:
https://github.com/openjdk/jdk/pull/15827#discussion_r1336145672

This test should disable Pass and Fail buttons. The Fail button should remain disabled: the test will fail automatically. Yet the Pass button may always be enabled, or it could be enabled only after the tester cycles through all the scenarios.