Larry, I've got a ton of respect for the expertise you and your dad have. But I'm afraid you're incorrect in this case.
First gear syncro carrier
They are "one sided" due to the fact that you cannot upshift to first, only downshift( milano and GTV-6 transaxles are set up same way) all the other gears can be subject to needing syncro effect for speeding up and lowering the speed of a gear relative to output shaft
A shift from neutral to first at a stop is effectively an "upshift". The input shaft is spinning faster than the output shaft and needs to be slowed down. This is where the missing bits in the carrier would come into play.
Without the missing side of the synchro carrier, the synchro cannot engage in this case to slow down the input shaft. Thus you get the Alfa first gear grind.
When sitting at a light in neutral and car idling, engine 850 RPM approx.
and you step on clutch and shove into 1st at that instant the slider is not moving, 0 RPM ( connected to output shaft i.e. drive shaft) 1st gear is at 262 RPM's and you expect it to instantly engage.
On almost every other type of car this scenario presents no problem. Since the synchro carrier parts are there, even if you shift quickly the synchronizer will engage and slow 1st gear to 0 RPM before allowing the gears to mesh. This is the reason all other cars have the bits that Alfa left out of the synchro carrier.
The Alfa transmission can only engage the 1st gear synchro to speed up the input shaft because the synchro only has one side to the carrier. That's why on the Alfa at a stop you need to either wait for the spinning to slow on its own or touch another gear to use the synchro in that gear to stop the spinning.
The fact is that every other fully-synchronized transmission has a double sided synchro carrier for first. There's a good reason for this.