There are only so many ways to accelerate a CPU by speculating.

I’ve written RTL that speculatively fetches data from memory in order to avoid bubbles in a pipeline. Not a CPU, but the concept is exactly the same.

If somebody had assigned me to a CPU project without guidance from a security architect and ask me to speculate reads, I’d probably have done the same as Intel.

The chance that the same guy did both CPUs is small. It’s just that it’s not an unreasonable way of doing thing if you’re not familiar with these kind of attack.