no way, i do not approve, heres why
gz is already a bigass base, with this enterance this would make the old enterances absolutly useless since everyone takes the faster route.

A better idea is to add barriers to shoot through for attacking gangs since defenders already have the defensive advantage. The basement enterance under the table could lead to another doorway up by the soda machines in the halls. This would provide a right flank. Barrier placements would be one in the middle of the T hall (the place where you go down into the next area after courtyard, looks like a T sideways).
This would allow people to break up gun walls without losing health.
last thing, add a barrier to the right side of the stairs to get to the ATM door. Most of the problems with attacking GZ is the box area with two doors leading into the flag room. If a barrier was added here then defenders would have 3 options,
1 destroy the person behind the barrier
2 move into flag
3 flank the barrier