Thanks for the post and welcome to the forums.
I wouldn't do anything that couldn't be un-done especially when the unit is under warranty. Electrical tape is the best bet since it is easily removed. I wouldn't paint the LED, but putting a tube or 'straw' over it as a cap sounds doable. The rear panel cover would have to be removed. Shouldn't be much of a hassle.
Either way, I wouldn't let this 'glitch' be a factor in your decision.
Abundant OTA television is what makes this country different from all others. Lets keep it this way. If you like Wi-Fi so much, OTA fits right in. After all, it is wireless.