Agnostic passive + soul tether

Can anyone explain the use of the passive agnostic with the belt soultether. Does the skill don´t invalidate belt efect?

Soul Tether:
Reworked so that it grants Immortal Ambition Keystone
Immortal Ambition
Energy Shield starts at zero
Cannot Recharge or Regenerate Energy Shield
Lose 5% of Energy Shield per second
Life Leech effects are not removed at Full Life
Life Leech effects Recover Energy Shield instead while on Full Life

The Agnostic
Maximum Energy Shield is 0
While not on Full Life, Sacrifice 20% of Mana per Second to Recover that much Life

Note that by saying "Maximum ES is 0", it is implied that you are always at full ES, much like a character with Blood Magic Keyston is always at full mana (despite having 0), or a Chaos Inoculation character is always on Full Life (having 1 on 1 maximum HP at all time, or being dead instead).

And... yes, they would annul themselves. The only vantage you would have with Soul Tether is to have the Life Leech effects not removed at full life. Considering, however, that Life leech switches to recover ES rather than leech, this won't make a character both at full ES AND considered to be leeching ES (for the purpose of Energy Leech support gem).

So... yeah, just a way to get overleech effect without being a Slayer, mostly