Who the hell cares? Take a deep breath of chill the fuck out and don't read so much into things.

I doubt they spent much time debating which browsers to add here, or that this came out of a strategy meeting with Zuckerberg. I wouldn't be surprised if this was designed before Chrome was popular (perhaps with some styling fixes since then).

Even if they did exclude Chrome intentionally, they are entitled to promote whichever browsers they want to promote for whichever reasonable non-evil reasons they want.