Sigh, I don't want it to spread like wildfire but hopefully with this information it will help towards countering these types of players while also not exposing it.
There is a time limit on it, it only lasts for 3 seconds. The method has to be repeated for another 3 seconds.
The method can't be preformed if the player is ran over and parked on top of, thus they can be killed this way.
Most players can't shoot and do the method fast enough, so there is a gap in the spawn protection that can be taken advantage of. The method can be done in cars, the entire car would flash just the same as a fresh spawn and the vehicle can't be blown up. I've seen players in tanks do this.....its the lowest of the low.
I found out the method by some rare/modded car collector who was really troll-y during a foot war. He explained it after we argued that he was cheating - his argument was that a glitch isn't a cheat. pft.