Well it's American immigration law, so who knows, really depends person by person. Like I legitimately think there isn't an objective answer to that question, it's a patchwork of laws and forms and guidelines that overlap and are interpreted by different people. Two different border agents can have completely different opinions on whether your work trip can be counted under a B1/B2 visa or not, and then USCIS (not CBP, border agents, but the immigration services agency, a completely different department) could have a different idea.