Because he didn't apply the Coding changes. Don't apply that coding changes as it also hides the "subcategories"
That solution was provided by someone in the forum.virtuemart.net but it doesn't work if you have any subcategories.
So; since you have subcategories, don't apply this code patch, retrieve your changes back to original. But instead use the solution that "copierx" has found.
Basically you are going to use a module to show "manufactures". And you will be using this extension:
www.nonumber.nl/extensions/advancedmodulemanager to limit the modules to be appeared on the designated manufacturer pages only. (normally you can set menuitem only to show the module, but this extension, lets you set any page to show or hide the module)
thehosrtdogs, if i were you, i wouldn't waste my time with it, sounds like it will take lots of time since advancedmodulemanager is little complicated to use and takes time.
Since this is also a problem of Virtuemart, and people are trying to find a solution in forum.virtuemart.net. Probably in the following Virtuemart releases, Virtuemart developers will patch it. If i were you, i would keep things as they are now and wait for the CORE patch from Virtuemart developers as it will be the most appropriate solution for sure.
Cheers.