I think that you have to take what the market gives you when it comes to house-hacking. 

So, things change a bit.If it is his personal home, there are more restrictions.For an investment property, if you take over his financing, read through the deed of trust (mortgage) and see how they handle transfer of ownership.

In our lovely state of WA once the removal is approved, it could take another week or two until the sheriff gets to the property and posts the legalese paperwork on the door(they are busy), basically telling the bum that he will be tossed on XX date. 

As you start you will want to take into consideration that many owners and hosts use more than just AirBNb to host their properties.  

Now, moving forward he offered for us to take it over completely.

If they can and are willing to provide ACCEPTABLE proof of their hardship, we may give then a few extra days (not weeks) at a step in the process.There is some merit to Jeff's claim that he is doing the work of 5 people - but, it won't take 90 days to go through everything.

The investors get much more profit out of the property.Recommend having a very open conversation with your FIL, expressing your interest in potentially taking over the property from him.

Take a look at what markets you are planning on starting in and make sure it is a growing market where the appreciation is obvious. 

Highlighting the strong profit potential and taking measures to address any concerns about costs, scope, or holding risks will make this an even stronger pitch.

Comps do not lie, if she pulled similar ones then that's what it is but if the agent did not take into account the bedroom and lot size that would change the value.