Eh, not necessarily. Would not be the first time skaters & their teams did not even make any attempts at finding out if something was possible and just assumed things. Like, considering that skaters have genuinely had planned program layouts that are not allowed, and those were high-level skaters & coaches too, I would not be surprised at anything at this point.
They would not have lost half the season. They, like others, could have done Challengers, which by the way get more WS points than JGPs. And after winning even just one Challenger, they'd very likely have received one or even two GP assignments, if they truly wouldn't have had any at the start of the season. Especially in pairs, where withdrawals are frequent and the replacement list short.
I'm not saying they are terrible for competing on the JGP circuit, I'm just saying that this narrative of "Well, we basically had no other choice" is not necessarily telling the true or full story. And yes, maybe they truly believe what they're saying, but that doesn't have to make it true, unfortunately.