I cannot tell you the amount of times my friends mentioned Green Bubble to me as an insult.
[1] https://www.wsj.com/articles/why-apples-imessage-is-winning-...
I just think the adult iPhone users that care about the color of a text message are pretty brainless. Care about something important.
If having Green Bubbles is a negative connotation. It would seem it's because Blue Bubbles have a positive connotation.
It does not seem like a stretch that someone talking like that feels elitist because they have an iPhone - which they express by your lack of Blue Bubbles.