I don't think suggesting to clients that they wait to vaccinate is breaking any law. I think there is a pretty clear definition of what constitutes giving medical advice without a license in most jurisdictions. It would be a HUGE stretch to make that statement be considered dispensing medical advice without a license. Lots of us here on curezone would be arrested if such statements were considered illegal. :)
But I agree that it is very risky to do so in the circumstances described - if nothing else, if the boss finds out, "you're fired" are probably the next words that will be heard.