If the Tick Tank stands still it it's really tough to kill. While moving it takes double damage.
In this game, repositions is vital to success. However the tick tank is the anti-thesis to this mechanic. The enemy is resisted from a hez on the map but the trade off is that they know you can't risk moving the Tick tank without endangering it.
If you were to build 3 you could hunker down on all three pads and it's game over, you'd never need to move them. It's a fun idea for base vs base like traditional CNC but i don't think it would suit this game very well.