if you've read Kasparov's book he talks about that. He had Deep Blue dead to rights because he found a line it couldn't predict, at least as he tells it. They patched the system between matches, which he considered unsporting.
This is not at all to take away from his incredible work ethic, and his position as one of the top players of all time.
In a normal world this is hardware you should still be able to go play a game against at either at some IBM building, the Smithsonian, or whatever.
There's a point where you stop playing the engine and are just playing the humans behind it through a thinly disguised proxy.
I don't think that line was reached here, but to avoid confusion, it's not unreasonable to expect that the engine remain frozen for the duration of the competition.
That happened in game 6, when the computer sacrificed a knight for a pawn to wreck Black's defense, which Kasparov thought the computer wouldn't do because it wouldn't look deep enough past the material loss, but the computer knew to do it because IBM had added it to the opening book. This controversy was separate from another in game 2 where Kasparov also accused IBM of cheating, where Kasparov expected the computer to grab some material gain but it played more positionally instead and Kasparov thought the computer wouldn't find that line without human intervention.
https://en.wikipedia.org/wiki/Deep_Blue_versus_Garry_Kasparo... https://en.wikipedia.org/wiki/Deep_Blue_versus_Kasparov,_199...