Firstly I think for the purpose of this discussion is important to clarify that is a huge difference between AI usage and quantum computing. Yeah they can actually make use of quantum computing probably in the future giving an AI model access to it but directly speaking quantum computing is very different from AI.

If it's about making use of an AI to create the scenario of a 51% attack well I don't think it will pretty much cut it. Basically a majority of the time if a particular body is able to pull that amount of power they may not necessarily use it to reorg the block.