This doesn't create a watertight guarantee, it doesn't make sniping impossible, but (as far as I can tell) it makes it much more difficult to pull off.
If we're considering the "simple" case where the architect is finishing their own "final hop" system, and it's the few minutes delay of them getting between the construction ship and the new station, then sure, it'd cover that and probably wouldn't need anywhere as long as 12 hours. That seems to be the case that most people in this thread are worried about anyway.
In terms of interface and side-effects, I prefer the "pre-reservation" options people have suggested, where the architect can start a new system claim at any time, including presuming the success of their current system, using a contact on the megaship - but of course if they don't finish this system within the hour, they won't have time to drop the beacon and get a claim timeout - that way the Architect doesn't have to remember to press a button which isn't currently part of the process, but anyone wishing to chain from their system in a different direction is unaffected entirely whether the Architect is online or offline, present or absentee, etc.
How often does your squadron swap factions? And for what purpose?
Since it's a new feature just available for the last three months or so, I doubt many players are designing their squadrons around regular use of it. But there are tens of thousands of squadrons out there, so if each squadron only changes faction allegiance once a decade on average, that's still multiple allegiance changes a day. Support doesn't need extra tickets for something which is currently self-service, when they could be helping people with actual problems out.
If I was running a bigger colonisation project than "one system" I'd probably use it quite a bit to mix up which factions each system had, rather than ending up with all of them having the same four. Mercenary factions (whether BGS, Powerplay, colonisation) might regularly re-align to fit their current employer, now that the option is available. There are potentially interesting uses for it for anyone not tied to the "one squadron = one faction" model of working - which with the removal of PMF addition, is perhaps going to become more common in future.