For me, the lack of credibility does not reside in the existence of an Instagram account, but instead in nakedly soliciting email subscriptions in a "privacy focused" post.
YMMV.
But if you felt you had a privacy focused message that you wanted people to hear, is soliciting emails really that bad an idea?
What is a preferable way? Ask folks to subscribe to an RSS feed or Signal group?
For me, the lack of credibility does not reside in the existence of an Instagram account, but instead in nakedly soliciting email subscriptions in a "privacy focused" post.
YMMV.