Leaving aside all questions about the safe and advisable use of aerial drones, I hope we can all agree that the notion this use constitutes a novel invention worthy of patent protection is risible and ludicrous.
I think they should change the patent rules so that any company that is awarded one has to sacrifice their CEO in a ritual disembowelment every year on the anniversary of the granting.
Helium is a gas that's markedly lighter than is an equivalent volume of most of the gases that comprise air (basically nitrogen and oxygen). So even when helium is under a similar pressure as air (like in a balloon), it accelerates (or exerts a force) upward. Like oil in water. Or like hot air in cold air.