The wording was meant as reverse direction compared to Gluttony, so the moveset keeps what it had, and only adds new squares onto itself. Base is stronger as + only for pieces that wouldn't have better square to be added on instead of move.
With these in mind:

• you can build army for synergy of "linking" your own pieces
• cost of lynx itself
• the "decreased" body count for trading (losing all copies at once)

I would always prefer to add better squares in range 2 then just move. And, maybe not melee, but ranged / magic, so they can threaten squares without needing to die for it (e.g. fireball, archer, ...).

The scenarios I originally thought could be typical:

• add strength to defenders which you don't plan to trade
• make superunit(s), that could ALL stay alive while helping you win
• after some trades / nearing endgame, improve your units if you can finish it without / before losing any

However, the longer I think about building army with this, the more I find it's too good / exploitable.
You can:

• link many units, either starting minions or - hello lich, and then transform them at once with gemini split
• make behemoth the last linked piece for mass immunity from minions
• make phoenix last linked piece for mass phoenix production

So while it is all nice to combine and imagine on your side, once it stands across the board, and you are on receiving end of it, all fun ends there :) .
Still, the ideas are nice to explore / theorycraft.