Redline sniping is a big problem. Many solutions have been thought of. None of which have a balanced or possibly negative affect on one of the teams.
Redline sniping isn't always useless. It is helpful when all the objectives are taken and your team is trapped but any thing you do to redline snipers will also affect people of different class.

Solution Problems
Redline sniping is quite annoying and in most cases not helpful nor counter-able.

Removing the redline. Would completely rid of redline sniping however would render a team completely unable to make a comeback.

Time Countdown in redline. The losing team be forced into a slaughter affect trap.

Unable to use weaponry. Same as the above the team needs to defend themselves. The winning team would be ready for when their weapons activate.

No WP gain. Though this would be useful it would be good for non sniping teams.

My Solution

New Line
During the battle introduce a new line.(gonna call it the yellow line)
The Yellowline comes before the red and has a longer countdown clone shutdown limit. Currently the redling countdown is 20 seconds the yellow line would be 30-40.
It would be designed to go along the area in the redline that is common to sniping.
Example: Skim Juntion Sector A, 6-8 all the way down would be the yellow line.
When a team has no objectives the yellow line which was could be walked in for 30-40 secs changes to a normal redline of 20 seconds.
Once the team regains an objective the line turns back to yellow so you can hunt snipers that are within the once prime sniping position.

No I will continue to red line sniper you and anyone else who thinks of taking away the red line. Have you ever played a serious sniper, you sit and pin the enemy to one area. I do not have time to shoot, stop scan the area, aim in and hope my target has not moved somewhere else. Stop with the anti sniper movement. You just give me more hatred to fuel the fire needed to head shot you. Do not like it, counter snipe.