One last one :) My apologies for not seeing that before as well!

getAvailability is the only algorithm that sets the presentation display availability. That algorithm also creates (and never resets) the presentation availability promise.

The presentation display availability will always be null the first time getAvailability is called so condition in step 7 that checks on the presentation display availability will always evaluate to false. The presentation availability promise will always be set in subsequent calls to getAvailability, meaning that the algorithm will stop at step 2, return that promise, and never reach step 7.

In short, unless I missed something, I believe that step (and substeps) can be dropped.

This did not happen before because there was no such thing as a "presentation availability promise".