Another agreement with Boom.
A driver in a simple traffic stop becomes physically aggressive, then intentionally sprays the officer(s) with an incapacitant. Given this it must be presumed that the perp's agitated mental state and aggressive behavior are indicative of malicious and violent intent, and now the perp has direct access to the incapacitated officer's weapon. It is both reasonable and logical to presume, if the reported circumstanced are generally accurate, that this situation presents an immediate threat of serious injury or death to both officers. As such, the second officer seems to have reacted accordingly.
More details and third party confirmation would be nice, but given the perp's recent legal history I see this as going away pretty quickly.
Brad