Well, to follow up: The response i got from Gantom is that they do terminate the chain. However, they way they phrased their messge to me makes me wonder if they didn't really understand what I meant by termination (which would be problematic). Their message text below:
Gantom Lighting said:
The GT22 does not have a DMXThru port, only a DMX Input. This means it would serve to terminate the DMX signal with no additional terminator necessary.
The problem I have with this statement is that they sell a DMX Y-adapter (which is problematic in and of itself) to plug in multiple fixtures, which, if each fixture has termination would add multiple terminators to a chain. All of this seems a little off.