> Also the bit manipulation extension wasn't part of the core.

This is primarily because core is primarily a teaching ISA. One of the best parts about RiscV is that you can teach a freshman level architecture class or a senior level chip building project with an ISA that is actually used. Anything powerful to run (a non built from source manually) linux will support a profile that bundles all the commonly needed instructions to be fast.

The fact the Hazard3 designer ended up creating an extension to resolve related oddities was kind of astonishing.

Why did it fall to them to do it? Impressive that he did, but it shouldn't have been necessary.