I stumbled onto a comment that was the most ideal solution for this “mod” but it seemed so lost in the pile I wanted to make a thread.
Just for some reference, I have a 93, and I use a Bluetooth radio transmitter.
For my personal liking, I wanted to find a way to ride in the LS while listening to Bluetooth music, without the massive 90’s antenna. It’s a way cleaner look.
I thought about replacing the head unit entirely so the radio wouldn’t come on and signal the wouldn’t antenna to go up, but honestly I love the look of the nakamichi system. And I wouldn’t know for sure if that would even stop the antenna from going up. I’ve seen people literally cut the antenna off , attempt to replace it with a shorter one, all kinds of things.

I wish I could give credit to the comment that saved me so much time and money, now for the “mod”.
on the left side of the trunk you can remove the lining out of the way, some screws near the tool box and some pins that hold down the lining. From there you can gain access to the radio receiver and antenna system. (Find some photos they are out there)
There’s two plugs, one is for the radio to turn on, the other is for the antenna to go up and amplify the radio signal. Simply unplug the corresponding plug, and the radio will turn on, but the antenna will not go up.
because I use a transmitter in my car, the signal is so close that my radio picks it up perfectly clear, and that leaves the car with a cleaner look.

Sorry it not more detailed in terms of instructions, I did it awhile ago and didn’t take photos, and don’t remember what plug is what. But it won’t hurt to do a little DIY if you’ve been thinking about this!

 

Have you tried to use the regular AM/FM radio since disconnecting the antenna?

Just wondering what the audio quality is like, if you've tried it.

I'm considering making a switch to disable my antenna when it's raining very hard, so water doesn't get in when while the antenna is moving up or down.

Since it uses the same connector, I am also considering disconnecting my keyless entry antenna (since I never use the remote key) and connecting my radio to the keyless antenna that is integrated in the rear glass.

Celsiors use their own antenna in the rear glass anyway for the radio, and do not have the telescoping radio antenna.

 

yeah it should be a simple as unplugging the radio antenna motor to not go up and down!

on my 97 i used the cell phone antenna imprinted in the rear glass as the antenna for the factory am/fm radio and it worked flawlessly.
you just have to link the coaxial cable from the cell phone antenna (right corner of trunk) to the radio antenna (left upper corner of trunk) - easy!

this guy did it similar to what i did.

 

Never knew what the names of those radio connectors were. Now I now. Thanks Timmy!

Metra 40-UV41 Motorola (Female), Metra 40-UV42 Motorola (Male) look to be the two.

The UCF10/11s are not pre-wired for the car phone unless it was an option, hence why I'm looking into using the Motorola connector from the keyless antenna in the rear glass.