Large differences between datasheets for the same part number
I would stick to the Microchip version of the specs for the following reason:
Microship added section 7.2 to the datasheet, which specifically addresses the HS pin spec and in particular the negative swing (cfr. revision notes).

Micrel probably forgot to mention that there should be a strict current limit associated with the negative swing spec and Microchip rectified that and set the specs on the safe side with some added recommendations on how to achieve it.