There’s no risk for a factory condition unit. This rumor started after people with units that had been dissasembled and reassembled had issues with vertical orientation. It turned out that it’s very easy to mess up the seals that keep the liquid metal thermal interface in place. So units that had been previously taken apart had liquid metal slowly leak, causing overheating and/or shorting.

If you haven’t taken the cooler off the mainboard, using the vertical stand is just fine. I haven’t seen any evidence of factory assembled units suffering leaking.