For me this line of thinking doesn't make a lot of sense. The Google Play option will always exist as it is a prerequisite for widespread adoption on Android. A

For me this line of thinking doesn't make a lot of sense. The Google Play option will always exist as it is a prerequisite for widespread adoption on Android. Also arguably, you're safer on F-Droid due to the level of vetting on that platform; so providing Signal on it is a good endorsement for general user safety and privacy. Either way, this isn't about only offering the application on Google Play or only on F-Droid; but providing the option for both. Non-tech savvy users will always pick the more familiar and easy option on average, Google Play.