I meant, while the text itself is encrypted, the metadata (which phone has signal installed, which phone is texting which other phone at what time, how often do they text, etc.) is available. If they use Google infrastructure these metadata are "sold" to Google whose main business is data/metadata.
Moxie also declared that the apk on their own website, is updated with the least priority, so the Google Play Store has their actual versions earlier. Even if you used the apk from the signal website directly this results in messages from the Play Store (which is often not uninstallable) to upgrade Signal although the internal upgrade says it is actual (as the real actual version did not arrive there yet). This draws Users back to the Google Play Store and enables them to harvest more metadata of users.
Additionally Moxie asked why people complain about Play store while using Googles OS which reveals a thinking of loyalty. That exactly fits to his odd behaviour regarding F-Droid (or any other places than Google Play Store).
Summary in two lines:
1) Signal is a sham which doesn't understand the spirit of FLOSS.
2) As long as it is not rebuildable without relying on FLOSS only it is not FLOSS.