The Giphy mention seemed really dangerous to me. Now I don't use Signal but I imagine it's 1) optional and 2) requests are proxified/anonimised through an intermediary (the Signal servers in this case). And why is this dangerous? Because this "don't build cool stuff on this serious app" is what makes people not use the app. It's creating boring, dull apps what stops them from becoming mainstream successes. If we are trying to make the public using secure apps because we believe in privacy, we have to make them appealing.
This is similar to the case of how nobody uses PGP because how horribly bad it is, UX-wise.
That said the rest of points he brings up are good. I just didn't like the Giphy mention, especially taking into account he didn't say anything else about it, he just brought it up.