Quite an important DfT announcement last night regarding the December timetable change, which pretty much ties with the time that message (above) was sent.
Much of the recruitment being done was to take account of the major shift in numbers required for the service which in many cases was due to double. Now that increase has been "postponed" until further notice to allow for a less chaotic introduction than the once Northern Rail and others introduced in May.
Note WMT mentioned in this article.
https://www.bbc.co.uk/news/business-44774539
Quite how this has, or is impacting recruitment remains to be seen, but slowing the recruitment process down for a few months does seem logical.