We have a situation here in-house whereby NOLOCK is written by default into every query.  I realise that is not a good idea but that is how it is and noone wants to change it so please don't shout at me.... 🙂

The point is that this behaviour (essentially a READ UNCOMMITTED statement) is overwritten by the behaviour of the HAG.  In this case it is irrelevant what the isolation level is, HAGs dictate the use of READ COMMITTED SNAPSHOT and ignores any attempts to try anything else.

At least that is my understanding.....

To that end, we have a lot of testing to do to ensure this behaviour doesn't interfere with our setup here.....