The "dog symbol" indicates "designated pet seating" and is intended/blocked for passengers with cabin pets.
If there is someone on your flight with a pet (or service animal) in business class that's where they will be seated. So IŽd only reserve 11H if being next to an animal (in a carrier) won't bother you.
And yes, chances are good you'll have no neighbor as passengers in business class usually select seats in advance and they can't select this one.

I really like this feature, and wish more airlines would offer it.

edit:
Generally, take anything you'll find on seatguru with a grain of salt. This information found there is largely outdated.
An FT member has taken it upon themselves to create a website offering vastly more accurate seat maps, find it here: https://www.aerolopa.com/