They'd meddle. Like with the tv show, where they nuked the capital of the NCR four years before new vegas. Problem is that the president of the NCR flies into New Vegas in the game from Shady Sands, so Shady Sands could not have been nuked.
Considering how bad Bethesda is at understanding the concept of time I wouldn't be surprised if the actual dates on events end up saying the bombs dropped before New Vegas. This is Bethesda after all, they literally had a plot twist around a person aging and to hide that twist they just made it so that another person didn't age.
The timeline in the show only says "The fall of Shady Sands". While that was unclear, Howard did explain it, and it's ridiculous to keep sticking to the whole "they deleted Fallout: New Vegas from canon" theory.
The timeline in the show says "the fall of Shady Sands" which was an event from 2277 to ~2281.
We can assume "the fall" started when the NCR decided to siphon water from Vault 33.
We know Moldaver was there, and fell in love with Rose (Lucy's mother) during that time.
Some time after, Hank (Lucy's father), arrived and failed to convince Rose to return to the Vault, but took Norm and Lucy from Rose, before detonating the Nuke.
The NCR is certainly aware of the risks involved with fucking with the Vaults. They must have been desperate to choose to siphon water from a functional vault without knowing what is inside.
My best guess is the NCR made a choice to grow Shady Sands as fast as possible without considering how to provide resources for everyone.
Personally, I feel they always intended the fall to be the nuking, but someone put the wrong date on the blackboard, and now they're trying to get the story straight again :P It does allow for some interesting possibilities, though.
If they changed the story even a little bit, it wouldn’t be the D2:R treatment. D2:R is literally the exact same game with better graphics, and the option to swap back to the OG graphics at any time.
seriously where are these people coming from thinking the story would change? hell, why even fucking change anything? takes more time and work to change things.