Jupiter is an excellent name for a dog - and not one I've heard. My in-laws work for a guide dog charity so I've heard almost every dog name under the sun. I've heard about a lot of Junipers but never a Jupiter - and Jupe sounds adorable as a contraction.
I hope as an aside she has a pretentious full name. We had a cat when I was a kid called 'Cuss' which was short for 'Custard' - which in turn was short for 'Custard Whiteboots The Seventh' - despite him being the first cat we'd owned. My father is a man with an excellent sense of humour.
The man in your story needed to be laughed at. Some viewpoints are so ridiculous its the only real recourse available. 'Fat shaming a beagle' will be the second song on my fictional debut album 'Whiteboy and the Gas Lighters'.