Think of this, Tanks drive up to this 10 second invulnerable spawn point, tanks don't leave, you don't leave. Watch you fall from the MCC and look whats waiting for you, 6 people waiting for you, oh but its ok you got 10 seconds...

Or... one could simply retune the Redline instead of removing it in entirety...
First by extending the area of all prior Redline areas back a ways, and then designating it with an orange border to differentiate the regions.

However, if you travel into the enemy orange line the further you go the LESS your maximum armor and shield become, and if you exit the orange, they restore to normal.

If you've ever played Runescape and tried the "Wilderness" before you'd know how these advancing regions work, but instead of going up a wilderness level, the affected party looses max HP relative to the tier they enter... so..
Outside of orange 100% all stats,
Area 1 --90% shield and armor (largest region mainly for deployment)
Area 2 (within handheld range of spawn) -50% shield and armor and -10% weapon damage
Area 3 (inside spawn proximity regions) -80% shield and armor and - 30% weapon damage

Defenses would be indestructible very-short-range manual turret systems that can target things within the orange region only, but loose power if the target is in a lower ranked region.

This way the complainers could run into the orange line to deal with troops/tanks they feel to be problematic. Would probably promote heavily dampened scouts.

Example,
If I had 100 shield and 100 armor, and ran into area 3, I would be left with 20 shield and 20 armor, and would not be able to heal over that until I left into area 2, then I would be able to heal back up to 50/50... and upon leaving all zones would be back to 100/100 maximum possible healing.
Zone auras are unable to kill players.