Sure it will. But there isn't so much they can do about it. Google could.
Still, people asked for an option to use Signal without Play Services, and here it is. Even if it will drain their battery a lot faster. Moxie actually said this beforehand:
> I expect it to have high battery consumption and an unreliable user experience
> I expect it to have high battery consumption and an unreliable user experience, but would be fine with it if it comes with a warning and only runs in the absence of play services.
So for those who are still running on devices with Play Services, it will still use GCM, and hence won't be a drain on the battery?
Still, people asked for an option to use Signal without Play Services, and here it is. Even if it will drain their battery a lot faster. Moxie actually said this beforehand:
> I expect it to have high battery consumption and an unreliable user experience
source: https://news.ycombinator.com/item?id=12883410