Not sure this is really an errata question, probably more appropriate for the Rules & such section. Nonetheless:
The bonus that some infected get to Initiative is listed under "Gained Powers" which are natural abilities that the character now has. Personally, I would rule it not an enhancement, so compatible. But it is potentially debatable, so it is best to discuss with your GM.
The classification of Critter Powers as Natural/Magic has been a long running issue over many editions of Shadowrun, so not really a new issue.