Hi Viktor - this is a limitation of how the connector is built today. I explained a bit more about this here:
One update I can give you, although it doesn’t help you today, is that Couchbase is planning to rework the Elasticsearch Connector architecture in 2017 anyway so that we can properly support ES 5.x, and we will likely get SSL support in when we do that. That work won’t start for some months though. Hope that helps,
-Will