I don't know how legitimate a complaint it is since Moxie et al have said that they would accept a well written pull request which provides similar functionality. But this just hasn't been forthcoming.
What I dislike about Signal mentions on HN is that aggressive posters conflate a number of different issues people have with Signal - lack of federation, reliance on Google push notifications, lack of SMS support, etc - and somehow lump them in together.
[Just to be clear - I am not saying you are doing this].
I mean, two things good about Signal is that it let's you chat with friends and family in a secure manner.
There are these following issues though: I doesn't federate, it relies on Google Push, it doesn't support SMS. Also, I don't like how Signal does [...]"
Is that already an invalid way to make an argument ?
I was trying to express frustration with posters who start out with a nebulous complaint like "Signal is bad and OWS is evil". If called on this they come back with "It allows Google to spy on you", if countered they come back with "it doesn't allow freedom to federate" and so on.
Rather than being a multi pronged criticism it's more like a bait and switch, with each new argument being deployed when the previous one is rendered invalid.
EDIT: of course the fewer attack vectors the better
The Play Services however pretty much amounts to a remote root shell open at all times. Google can remove or modify code at will, and they have been known to do it in practice for spyware removal. I can understand how an activist finds that problematic.
