Your assessment of proof by contradiction is flawed.
I've been working on verifying the proof of result #195, which proceeds by contradiction. It uses a fairly standard proof technique, but in a way that is novel as far as I can tell. Basically, they want to show a certain class of modules cannot exist. They do this by showing each module has a bridge to a related object that is easier to study, and then use the bridge to transfer data between them. This is pretty standard. What is novel is how the bridge and related class of objects are obtained: they pass from a certain class of modules to coherent sheaves on a related object, and then perform some other formal operations. Next, they establish numerical constraints that any hypothetical module would have to satisfy through this bridge. Then they construct a specific ring whose geometry makes those constraints impossible. Ergo, no module of the specified type can exist over that ring.
But this isn't like it just produced a contradictory object that it can plug into a calculator to check if it violated some known constraint. The proof technique is standard "M sucks, so build a bridge to N that doesn't suck, then transfer data between them." But actually pulling that off is not so straightforward. So result #195 did produce a counterexample, but it did so by creating a transfer principle, and then it used it. It's not like it produced an object with three angles, summed them, saw they didn't add up to 180 degrees, and concluded it isn't a triangle. The mathematical machinery that produces the contradiction in #195 is actually pretty impressive. Thus, I think it's a mistake to classify the contradiction results as easy somehow. Also, contradiction is the most straight forward way to disprove something, so if you feed an AI model a false conjecture it's naturally going to gravitate to contradiction. Not because it's somehow less creative than a person, but just because that's the most reasonable way to complete the task.
I should also remark that a lot of #195 is out of my area of expertise, so this assessment may be flawed. Still, this is what I've gathered from it so far.