Tumblr - both as the userbase and as the company - has been pretty “cool” compared to Facebook/Instagram (which isn’t a high bar, really). I think most people are indifferent to favorable on letting them in here if they decide on doing that.

I think they’re “getting their feet wet” with federation with an official WordPress plugin (Tumblr is now owned by the company that develops WordPress) first, before deploying it on Tumblr.