Which is interesting as they were only granted that patent in March... Technically a GoPro mounted to a drone is a "drone camera" that can be interchangeable - good luck with that one! Also they appear to be suing on the basis of either "follow me/watch me" mode which is done by just about every manufacturer (and is the main selling point of Lily, for example) or on what RealSense can do - despite it not being released to market yet.
As I've previously said, this is going to go the way of Apple v Samsung and Colin Guinn v DJI - the lawyers will spin it out for several months at $$$ per hour and then there'll be an "amicable" settlement, the details of which will not be revealed, and in the meantime there will be no injunctions or restrictions on trade.