I've actually heard this asked a few times on chat, and I'm downright curious - Who is this David, and why is his use of the SE Android app important?
David is the Vice President of Engineering for Stack Exchange, Inc. Despite the name, this does not mean he is responsible for all engineering vices - it just means he directs all development work.
Unlike many of you poor, lost souls, David is proud to use something other than an iPhone.
As you can see from the picture, David is a very angry man.
David once had a desk that responded to his voice commands. Does your desk raise or lower itself in response to your utterances? I didn't think so.
A radioactive spider once bit David. Now it puts on a costume and pretends to be a Vice President. Unfortunately, it didn't read my clarification regarding the use of the word "vice" above - so be very careful if you ever encounter a spider wearing a hoodie.
The above are all of the primary reasons, but it all may make a smidge more sense (well, not really) to those familiar with the "Lucas uses Venmo" campaign that no one understands which is all over the NYC Subway system: