Yes, they are valid via Wilmslow. As well as via Manchester, as it happens.
Mauldeth Road has two routeing points, either of which can be used, Manchester (Group) & Wilmslow (Group). The only caveat is that the routeing point used must pass the fares check rule, which sounds more complex than it is - essentially the fare (as defined in a previous version of the National Fares Manual, NFM 64) from the routeing point to the destination must not be greater than from the origin to the destination. Even more simply, you can't choose to go the "wrong way" when you have two or more routeing points to choose from - “wrong” as in more expensive, essentially.
For Tutbury & Hatton, Wilmslow fails the fares check rule and can't be used as a routeing point from Mauldeth Road. The fare from Wilmslow is greater than the fare from Mauldeth Road.
However anywhere more obviously "south" such as Crewe-Shrewsbury etc. will be able to use Wilmslow as a routeing point. The fare from Wilmslow will usually be less than the fare from Mauldeth Road.
The Routeing Point Calculator at
https://data.atoc.org/routeing-guide sometimes helps. In the specific case of Ludlow it shows that both Manchester and Wilmslow pass the fare check rule:
View attachment 168067
The fare from Manchester is the same as the fare from Mauldeth Road, so it's not more, so it's valid to use this routeing point. The fare from Wilmslow is less, so that's definitely fine also.
NFM 64 is used because it's a historic reference document, it seems strange but if you used the actual fares then things would change all the time. It leads to the strange practice of inventing fares for NFM 64 for stations which didn't exist when it was created, just so the rule can be applied to them today.
EDIT Note that, in the case of Mauldeth Road-Ludlow via Styal and Wilmslow,
all this discussion about fares check rules is OTT, because the shortest route will be via Styal and Wilmslow, so it's a permitted route. However the rule is needed to allow travel via Manchester, which is 5.25 miles further. As is the case for every other station between Mauldeth Road and Manchester Airport - the route to Ludlow via Manchester Piccadilly is valid.