Inspector says that split bolts shouldn't be used on live connections. Right or wrong?
If you are discontent with the quality of wire nuts, you can go to a proper splice block.   These are my go-to for anything larger than 6 AWG. 


Source

The wires are inserted in the side, then they are tightened down from the top holes with hex keys to a specified torque.   The holes where the hex keys go in are then capped.  If the wires are near the largest size the block permits, there is nothing exposed at all.   The quality of the connection is exceptional.