I can’t find anything that says they aren’t excluded. You’re using logic that makes 100% sense both ways or 0% sense both ways. So it doesn’t work.
They don't have to be included by language since they worked after 8/1/18 under the extension they are included naturally by being employed on those dates. There would have to be specific language stating that the separated employees are not entitled to retro pay.
The new contract lists a start date of 8/1/18 right on it's cover page.. It is stated that all economic improvements are retroactive until 8/1/18.
An attorney would have to review the terms of extension to be certain but so far I have seen nothing that would prevent separated employees from getting retro checks.
I have no skin in this game other than not wanting to see former employees get screwed. My opinion is based on the information I have seen, that's why I keep asking if somebody has seen the language that excludes them and if so please post it.