That might be true, but the votes (not seats, first past the post, almost guarantees people aren't represented): Labour: 9.7M Conservatives 6.8M Reform: 4.1M Liberal Democrats 3.5M
The point clearly stands that had Reform not been a thing, 2024 would have been a conservative landslide.
What we got was a Labour landslide, what we should have got was some coalition.
Yes, though I'd be careful about assuming that votes are Conservatives <-> Reform on a left-right median voter model. The other aspect that Reform has (and will have at least until it forms a government) is anti-system/populist credentials. Labour had a little of that last time (they are a deeply establishment party, especially under current leadership, but they were coming off a period as very public opposition to the government and the current state of things) but will have very little next time.
It's certainly not a given that all the 2024 Reform vote would have gone to the Conservatives: a good chunk of it would have likely been disgusted abstention, another chunk to other anti-system parties (mostly of the right fringe, I suspect, but not excluding the Greens despite wild ideological differences), and likely a further (if smaller) chunk to other parties which were simply not the Conservatives (including Labour and the Lib Dems).
Edit: the best analysis on this is likely to be in the latest volume of the long-standing The British General Election of XXXX series, which has just been published online[0]. I haven't had time to look at it yet, though.
As the sibling comment said. You are making the assumption that every Reform voter would have held their nose and voted Conservative instead. A lot more people would have stayed home I think. I don't think anyone thought the Conservatives could win and that includes the Conservatives themselves.