The kind of proof I'm looking for is: "Look, here's how we access the radio. Here's the set of AT commands. Here's the NVRAM layout. Here's where the IMEI is stored. Here's what happens when we try to overwrite it. Here's the demonstration that it gets restored from OTP/efuse areas".

Then I'll believe it. After I try replicating the same process myself.

Until that, the claims are empty.