You are mistaken, or they misunderstood your question, or you misunderstood their answer.

What it boils down to is you are essentially wanting to log time in an airplane you are not rated to fly.

Your in depth paste job about acting and logging is wonderful reading...
show us the part where you can log time in something you aren't rated in.

This section is for commercial licensed pilots flying right seat in aircraft not requiring a type rating to be able to log their legs toward the time requirements for the ATP. For example, Cape Air has FO's in the C-402's. You are a licensed multi-commercial. You may log your legs towards the PIC requirements for the ATP, since you ARE licensed and rated to fly that airplane.

You can not log what you are not licensed or rated for.

There is another section in the FAR's which talks of performing the duties of the pilot in command under the supervision of the PIC... it has already been established that the "duties of PIC" include more than just simply flying the airplane. This section is typically used by baby captains to be able to log their first 25-75 hours as PIC while getting their IOE. They ARE performing the duties of PIC, under the supervision of the PIC (the check/IOE airman).

You aren't going to get around the 250 PIC requirement this way; and rightfully so. Think about it. Would you really want somebody with that little command decision making time flying your family around in bad weather? The regs exist for a reason, and the reason is generally safety or common sense related.

Perhaps when you really do upgrade B76 you'll understand how much more involved it is than learning to use a tiller, sign a release, and do a few extra sim maneuvers.