You just don't seem to understand how the service you are using works and guess what. Its different then pure PG. It was not designed to work with your smart-card as it is not primarily about that.
Guess what, other people like me just realized that Keybase was not designed to be used like that and didn't use the smart-card together with Keybase.
I guess you can fault them for not saying that explicitly but since the made no mention of smart-cards and didn't evolve the security model in that direction it was pretty clear that that was not what they were about and therefore I did not expect it to be optimal to be used like that.