Sorry, just saw your message to me. (I never seem to focus on that part of the page.)
Good news that you are working towards a diagnosis. I agree about having questions about a PLS diagnosis since he has atrophy... widespread, as I recall. But yes, atrophy is generally considered a LMN sign and not present in PLS which is only upper. Of course, there seem to be exceptions to every rule when dealing with MND. Good luck at Mayo. There is a very nice Courtyard by Marriott very, very close by. Expensive, but if you have Marriott Reward points, it's convenient.
If your husband has a new EMG there (which is normal), the NCS will probably be done by a tech, the EMG by one neuro, then your consult will be with another neuro. And the consult can be pretty quick, so have your questions written down and ask them all. Their EMG chart is very complete, so be sure to get a copy of it (or at least sign the forms to have the EMG sent back to your neuro or PCP.)
Good luck!