The pre-existing Reform/Alliance is part of it yes. But I believe there's also a significant "PPP" (Pro Pierre Poilevre) element that has been cultivated and groomed via social media, that amounts to a wholly new "faction" of the party, separate from the traditional Reform / PC camps. It's not a perfect heuristic- but let's use "Members who supported Peter Mackay in 2020" as a proxy for the PC wing. That number is/was just shy of 53k. Poilievre signed up 300k members and won every single riding outside of Quebec- and has likely grown his support in the 3 years since (if my rural Ontario social media feed is any indication), + shown a tremendous ability to fundraise from this group, get this group out to rallies, etc.
If he can keep them mobilized / on side the PPP + R/A camps absolutely dwarf the traditional PC camp. Absent an immediate caucus revolt, there will be a span of months between the election and the mandatory review/vote at the national convention. Months where he'll have control of the communications apparatus, and the party warchest at his disposal, presumably with Byrne running around in the background. That's an uphill battle for Ford/other challengers to wrest control of the necessary delegates to even trigger a leadership contest.
I hope I'm wrong, but I think the CPC grabbed a populist tiger by the tail and is now along for the ride.