Techline says my SPS programming issue for my amp is a comms issue?

Sure, here is the SPS servicing programing procedures:

Service Programming System (SPS)

Review the information below to ensure proper programming protocol. Check out the images (below). Please let us know if you need anything else to get the problem fixed.

Perhaps I should have shared that I am very comfortable with the requirements and SOP to be successfully complete SPS programming. All the things you sent me have been validated to not be the problem. I am looking for master techs that have encountered these SPS errors before and can share how they resolved them.

Okay, I will see if our other techs can help.

Those codes are specific to the SPS program. You need to contact the help desk for GM Techline to diagnose the programming fault.
Be sure your battery is good and fully charged. It must register 12.6 volts in order to program.

At the risk of sounding ungrateful, what has been offered up to this point are the basic tips that even any entry-level tech would know how to do. If you do not have experience with these specific errors, then please refrain from responding. Techline does not have answers either hence the reason for reaching out to a broader audience.

The programming error code information is only available to Techline. Try disconnecting all other programmable modules, then attempt to program the amplifier.
I suspect the cyber security error could be a firewall issue.

Thanks. I have heard pros and cons for this approach. There are some who say the body control module plays a part in the comms chain and should never be omitted. Have you heard this?

There is that possibility. This is just an easy way to prevent other modules from preventing the programming event. I have used this method before on vehicles that were struck by lightning.
The amplifier isn't a module that is a one-time program module. The amp is also on the low speed comm bus.
You should disconnect JX205 and JX207 comb connectors to eliminate all modules. Install jumper wire from terminal D on JX205 to terminal E on JX207. This will link the amplifier directly to the low-speed bus at the DLC. This way, you don't need to access each individual module.

Thanks DENNYP!