The Northern Manchester - Huddersfield - Leeds timetable does not show the eastern destinations of the TPE 5tph between Manchester and Leeds. However, it does show that the Piccadilly terminator (currently the Hull service) will run fast between Huddersfield and Stalybridge in off-peak hours, but call at Slaithwaite, Marsden, Greenfield and Mossley in the peaks. Together with the Huddersfield - Piccadilly stopper, that gives those four stations a 2tph service in the peaks.
The route swap detailed in the tweet will give Hull quicker services to/from Manchester as well as Liverpool, particularly in the peaks. Albeit serving Victoria not Piccadilly.
The downside is that Scarborough loses its longstanding direct Liverpool service and has slower Manchester journey times, especially in the peaks. While York goes down from 4tph to 3tph to Victoria, although it gets 2tph instead of 1tph direct to Piccadilly (Saltburn - Airport and Scarborough - Piccadilly).
Rumours on the Nova 3 thread suggest that the LHCS sets are to be transferred to the Saltburn and Cleethorpes routes, with all Scarborough services worked by 185s. 185s would be better suited to the calls at Slaithwaite, Marsden, Greenfield and Mossley.