No, I get notifications from tapatalk too, even though I can't log into FB from tapatalk. The AutoGuide app is just a custom version of tapatalk with a bunch of ads slapped on it. So essentially tapatalk push notifications are still going out.
If you don't have a lot of forums in tapatalk I think your best bet is to remove it from your iPhone and reinstall it. There is more than likely some sort of config file in the background that is someway or another communicating with FiskerBuzz.
I've run into issues similar to this in other apps and a remove and reinstall fixes it.
To discontinue these notifications, FiskerBuzz.com needs to be removed from the list of forums in your Tapatalk app.
The removal process is different on different versions of the app. On my iPhone, with the newest version of Tapatalk, one would go to the forum account list and use the edit button in the upper-right corner to select a forum account to be removed.