It turns out I was actually wrong! You can achieve this with a level 5 Grendel as well.
While this is good piloting, the deciding factor seems to be bad AI. Zig never really needed to vent, it should have just dissipated normally. Zig easily out-damages your blasters and his phase cooldown is short enough to re-phase in case of Reaper launch. Zig also probably had effective speed advantage to stay away, and didn't use that (less base speed, but it can afford to spend much more time in phase).
Perfect behavior would be not to phase continuously at all, and just use cloak reactively vs blasters and reapers. Though AI isn't allowed to use perfect timing like this most of the time (with some exceptions, this sort of instant reaction is allowed for Damper Field use).
On a side note. Switching linked/alternating fire mode in combat should be a vanilla feature (there is a mod). Because switching to alternating is necessary to counter some of these tactics, but is sub-optimal most of the time.
