Send Feedback via Nexus 4 and tell them you are "Missing Marshmallow :("

Yeah, much likely it won't have any effect. But what is to loose? 15 Seconds? Just go (stock android, 5.1.1) to:

Settings -> About Phone -> Send Feedback about this device

and send them a short message like "Missing Marshmallow :("

Miracles can happen :angel: