The fact that you're a software engineer is irrelevant. You're not a software engineer for Apple. I, as well as many others on this forum, have similar training and experience. I've been doing this for over two decades, involved in both the software and hardware side, both on military and civilian equipment.
The only thing you're even close on is that it is a hardware limitation. But your error is in your assumption that the limitation is because of the design. That's incorrect. The limitation is because of the manufacturing defect in a small percentage of these devices. Defects are not part of a design. Every person I personally know that is using an iPhone 4S running iOS 7+ has no problems. I have only personally seen, out of dozens of iPhone 4S units, one wi-fi greyed out issue. And a reinstall of the iOS (even different versions) did not resolve the issue. However, the issue was resolved immediately with a device replacement.
If it's a 'software' problem, then explain why:
A) Only a very small percentage of devices running the exact same software have this issue.
B) Replacing the device and then running the exact same operating system, as well as the same user data, almost always resolves this issue.
The defective wi-fi chips involved have a lower than acceptable tolerance for heat buildup. The update process generates more heat than normal operation.
The code of the software is not directly affecting the wi-fi chip. It is the heat from the update process that reveals the hardware defect that has been in place since time of manufacture.
I've already posted the best possible way to get Apple to replace the device if it is outside of warranty. You are still chasing a red herring of your own creation.
The main topic of this discussion is how to resolve the issue, and per the terms of this forum, such discussion must stay within the Apple approved methods. So, let's recap, because this (and other threads related to this issue) are far longer and convoluted than needed.
A) If within warranty, get the device replaced for free via Apple.
B) If not, then pay the appropriate out-of-warranty fee for a replacement.
C) Request a one-time exception to the OOW fee from Apple, preferably using the script I provided.
D) Live with the lack of wi-fi on the device.
E) Seek a third-party repair solution, which will void any future service options for that device from Apple. Additionally, detailed discussions of such options are prohibited on this forum.
F) Purchase a replacement device out of pocket, either another Apple product or one from a different manufacturer.
There are no other options.
