negotiating can send a signal that you don't value the other entity as highly as they value themselves. it's one thing to negotiate over the price of an apple, say, because the apple doesn't have feelings. but if you try to talk down the compensation package for a potential employee/advisor, particularly one who would likely become a star contributor, you can hurt their feelings and/or cause them to seek employment elsewhere. you can always buy an apple from somebody else, and the store/vendor can always sell that apple you passed over to somebody else. but as a laborer, you have only so many hours in the week you can sell to somebody else, so in general it's in your best interest to get the highest compensation you can.
So negotiating as a general rule is good. But in specific cases, where you're dealing with an opportunity or "non-commodity" thing, no, negotiating can sometimes be bad. That was his whole point.