Unsurprising really. It seems fairly apparent that gravity merely influences the geometry of the substrate in which all known forms of matter & fundamental forces operate within. Something would have to seriously be fucky for antimatter to act counter to that geometry given it is comprised of similar particles with opposite charge. I’d assume astrophysicists know this, but wanted experimental proof for what seems to be straightforward logic from things we have experimentally confirmed.
The real question is what form does this geometry use to exert influence on the matter operating within curved spacetime? How is that information carried and how does gravity interface with that?