I can totally emphasize with the situation and the different reactions.

Just want to emphasize the part about separating responsibilities according to what you are each good at and stick to those.

For this pursuit I'd emphasize the strength of your team and specifically your PM. 

They seem to emphasize appreciation, the areas of value add on the property, and tax shelters.

I would interview multiple STR management companies so you can get an idea of what they offer, emphasize and their experience so you can hand off your asset in the hands of a reliable, intelligent and effective team.

This point can't be emphasized enough. 

Have you tried to send him an official letter emphasizing the importance of doing so?

FYI, tenant-occupied properties can be great deals but to emphasize once again, you need to perform your due diligence and make sure all of your ducks are in a row.

In our last phone call with the agent, before the sellers made their final decision, I emphasized on my story and took advantage of that rapport which I had with the agent and the sellers.

They all put emphasizes in building a sellers network, even before you start finding properties.