If the repo is configured to disallow merging until builds pass, the wait-for-build option will not appear, although this seems like it should be part of the functionality. The problem is in this code:

		// The user cannot merge
		() => !select.exists('[data-details-container=".js-merge-pr"]:not(:disabled)')

The merge button might be disabled because builds haven't passed yet, not because the user doesn't have merge permissions in general.