Hope they only say we won't stop you, we will just void your warranty. You buy a product, you should own a product. If you want to fly it off the edge of Niagara falls or into an erupting volcano, this is your choice. So if you want to Mod your Drone (HW SW or Firmware) I would hope they don't care as long as we all agree no Warranty. Mods are what makes cool stuff cooler.
Does it really matter to you what DJI really thinks? I wouldn't think they would care one way or the other what one does with their drone. I would think "cosmetic" type mods would not be an issue in regards to warranty. Just the same as Harley Davidson selling their bikes off the showroom floor yet they make a larger profit selling the tons of accessories or "mods" to their bikes. Now if you owned a new Harley or any other manufacturer and get into engine modifications or intake\exhaust mods bought from 3ed party sources, then warranty claims could be put in jeopardy. It's your drone and do what you want with it.