In a premises as small as described there probably will be very little benefit in AFD. Having the only real risk enclosed in FR with a HD in place would be a clear benefit though.
Regarding the placement of the risk relative to the door in question, the fire doesn't have to be by the exit to cause a problem. The station nightclub fire is an example of what can happen when too many people want to use the same exit, (granted, there were other big issues with the place regarding using pyrotechnics inside, surface coverings etc) and it could easily have been of such a layout regarding fire loading etc that there was no chance of losing the main door whatsoever. The main entrance/exit wasn't taken out by fire, it was taken out by the number of people trying to use it and the urgency that will have been evident.
It is an extreme example I know, but it shows why there needs to be a good thought process behind any decisions that are made. You need to be able to qualify that people will remain calm, and won't be threatened by fire at all. The reason for the door widths and the theoretical 2.5 minutes is not just related to the time it takes the national anthem, it is to keep a reasonable flow rate through the door that people are happy to move at without feeling like they are being put at risk. (i.e. If you are trying to escape, and you join a queue that doesn't seem to be moving, that is when the pushing and shoving starts)
Forgive me for giving an extreme example. I am not saying that we should stick rigidly to the 60, but things are sometimes not quite as simple as they seem, but a good risk assessor could account for these details, as seems to be happening here.