Loading and unloading data from disk is highly preferable to sending the same amount of data over a bottlenecked Thunderbolt 5 connection.

No it's not.

With a cluster of two 512GB nodes, you have to send half the weights (350GB) over a TB5 connection. But you have to do this exactly once on startup.

With a single 512GB node, you'll be loading weights from disk each time you need a different expert, potentially for each token. Depending on how many experts you're loading, you might be loading 2GB to 20GB from disk each time.

Unless you're going to shut down your computer after generating a couple of hundred tokens, the cluster wins.