I think people might be reading too much into this and jumping to conclusions.
From the NOTAM there's nothing implying that zone transits will be banned, however due to the extra workload on ATCOs there will be the slight possibility of restrictions operationally. As is normal with any operating environment.
Probably nothing to see here, move along, unless there's the odd bad day when Fred McController phones in sick, traffic gets busy, GMC and TWR are combined, a foreign pilot who's never visited GLA before can't understand a readback and blocks the frequency for 5 minutes trying to readback a clearance multiple times and someone declares an emergency, in which case Joe Bloggs in his C152 will be politely told to go around the zone or asked to orbit for a wee while. Any of which can happen at a normal day at any unit with a Class D zone.