Sam,
Thanks for response. I wish to reply twofold.
Firstly, you state that you are 'completely aware of AIrbnb Policy' on 3rd PB.
However, the 2 examples you give (80 year old woman & friend returned from Afghanistan), rather suggest that you don't understand how the Policy operates in reality.
There are 2 errors.
a) 'I highly doubt that AirBnB wants a host to get permission in situations like that'
In fact, in this situation or any other, a Host isn't obligated to get permission. It's the Guest who must seek the permission!
T&C, 4. 14 clearly cautions the person who is doing the booking: 'unless Airbnb explicitly permits otherwise, book any Listing if you will not actually be using the Host Services yourself'.
b) 'I imagine if I would have as you said: "denied access on the doorstep" to either one of them people AirBnB would have gotten really upset.'
No, they wouldn't if the person booking had not sought permission. On the contrary, AIrbnb cannot possibly be upset with the Host; they would be rather preoccupied with enforcing their own T&Cs!
We may draw the conclusion that you don't understand the workings of the Policy because to date you have been fortunate enough not to come across any problems related to this Policy.
The limitation of your experience is a part of the second point.
I note that you have not even Hosted for a year.
I further note you rent out two places, neither of which you live in.
Compare with my experience, having hosted 5-6 years, probably taken 5 times the amount of bookings you have to date; and most significantly, that I am a-live-in Host. I go to bed and wake with Guests in the house, I share facilities, toilet, bathroom, kitchen, and so on. Moreover, I rent several rooms in the house, so often there is more than one set of guests together, and one can never predict the chemistry. All in all it suggests that I've had a myriad of experiences you have not encountered and never will do.
By and large they have been very good experiences. But inevitably problems arise from time to time. Though few and far between, the fact is a higher number of incidents arose from 3rd PB. I set aside examples and analysis of the reasons. Suffice to say, that I have come to the conclusion that there is merit and even wisdom in the Policy.
Consequently, I am now most cautious to accept 3rd PB, and only do so selectively and with the knowledge of Airbnb by means of getting the Booker to accept 'full Liability in any eventuality'--Morevoer, If the disclosure of 3rd PB is only post-booking, I think twice whether to continue the booking, because it indicates a lack of transparency by the booker which tends to herald futher problems.