Yep. The loophole is not hard to close, they could restrict the exemption to standby generators which only operate (1) in the event of a grid outage, and (2) for testing purposes.

For a genuine off-grid use case (eg: very rural locations), they could add a new exemption which allows installations up to X kW capacity per site where local grid connections do not exist. Set X large enough that it won't negatively impact applications like cabins or nature retreats, but small enough that it's not useful to a large operator like a datacentre.

Of course, this all requires a functional Congress... so good luck.