Hello,
Only the usage of the vendor root allow such kind of restriction.
Because that root indicate which category belong to the vendor and he has the right to edit that category and the children.
Otherwise, the vendor would have access to the entire tree.
And adding some ACL to indicate which category can be edit by whom ; would be a nightmare of configuration and I don't even know how could be an interface for the settings.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.