Also worth noting that the Approved Document needs to be read in full not cherry picked.
As example it specifically says that certain parts do not apply to prisons - for fairly obvious reasons!
But before the section that Mathew quoted there is
Door fastenings
5.7 In general, doors on escape routes (whether or not the doors are fire doorsets) should be either of the following.
a. Not fitted with a lock, latch or bolt fastenings.
b. Fitted only with simple fastenings that are all of the following.
i. Easy to operate; it should be apparent how to undo the fastening
ii. Operable from the side approached by people escaping.
iii. Operable without a key.
iv. Operable without requiring people to manipulate more than one mechanism.
Doors may be fitted with hardware to allow them to be locked when rooms are empty.
In places such as hotel bedrooms, locks may be fitted that are key operated from the outside and manually opened from the inside.
If a secure door is operated by code or combination keypad, swipe or proximity card, biometric data, etc., a security mechanism override should be possible from the side approached by people escaping
So, it is about having a fire risk assessment that justifies a proportionate approach.
No multistorey shop is going to leave all its exit doors open in the event of the fire alarm going off - just tells the criminal to set off the fire alarm and have free access when all the staff are at the muster point!
...and hence 5.7 above is about making sure that those inside can get OUT - but doesn't say that someone should then be free to get in with no restrictions.
P