There will always be security issues, so "but security" is not a reason to prevent a consumer from doing whatever they want with a thing that they purchased from you (I'm of course just speaking morally/ethically here since there's no legal provisions preventing that in most places).

If I pay you for a product, you have no moral right to tell me what I can and cannot do with that product, up to and including messing with the firmware, installing known-bad firmwares, wiping it and building my own firmware, whatever I want. It's mine, I paid for it, stop violating my private property rights.