As written n the Whitepaper, they're using an escrow service. The escrow would not release the money ( and Giga would not release the tokens) until the pods are actually constructed.

There might be a little confusion with the term "constructed", as a pod can be constructed, but not ready for hardware deployment, for various reasons, including unexpected ones. The Batch 1&2 tokens were released when the pods were physically constructed, but the problem was with the various inspections and extra requirements that appeared (unexpectedly). That's how we have the current situation: Batch 1&2 tokens were released despite Pods NOT being operable, despite the fact that they were indeed physically constructed.

The idea is they CAN'T issue the tokens for Batch #3 yet, even if they wanted.