I apologize in advance for subjecting you to Mika and Joe, but to witness someone talking about what he "inferred" rather than the correct "implied" is just too good to pass up.
Imply and infer are not interchangeable. The speaker does the implying, and the listener does the inferring. If he inferred it then his writing might imply it based on his own inference. Does his book say anything that implies it?
And easy way to remember is: Only you can imply, and only I can infer.