The opening page of HiveSigner.com says: "Hivesigner neither store nor has access to your private keys."
You probably should change it to "Hivesigner neither stores nor has access to your private keys."
I wish you maintained services for both platforms. However, I realize that trying to do so would create a mess. At the time of the hardfork, everyone had the same credentials on both platforms. But these credentials will rapidly diverge.
Thank you for the suggestion, will fix that.