While I generally think constructive criticism is usually the right choice, I suspect Github will never get the message unless there are some very strongly worded criticisms. In Andrew's defense, he did post some constructive evidence of things he considered problematic.
The most effective message GitHub can receive is when they don’t get to invoice you.
GHA in particular is a hot mess, I’m as surprised as a decade ago that anybody is using this crap. IMHO it’s bugs as a service kind of product, and the bugs start at the core design with the ‘pretend yaml but actually an unholy mix of shell, js and json’ language.
A high-profile repository like Zig moving off of Github is as loud a message as one can give. Tossing in "losers" and "monkeys" only muddies the delivery.