That does not convey "placed in a bag, backpack, or in an overhead bin" in any way.
If a computer cannot simply have its lid closed before being placed in its bag it simply is /not/ a laptop. It should not be advertised as a laptop and it should have a big f&%ing warning on it telling you that it will break if you treat it the way you expect to treat a laptop.
Either Dell didn't know they messed up their laptop design and when they found out made the decision not to recall the faulty product or they knew and sold it fraudulently. "This is a laptop - but we know it isn't and will break if you treat it like one warranty void, sucks if you believed us."
Either way Dell made the decision to screw their customers. There's no getting around that. It's a choice they made.
Not sure about user expectations but it’s the first time I heard about laptops overheating in standby mode.