That something we're trying to do too. However disabling clients connections (closing thrift and native ports) does not prevent other nodes (acting as a coordinators) to request it ... Honestly we'd like to restart a node that need to deploy HH and to make it serve reads only when it's done. And to be more precise, we know when it's done and don't need it to work by itself (automatically).
Don’t want to serve reads? Disable thrift and native proto, start the with auto-bootstrap set to whatever you want but thrift and native proto disabled, then enable thrift and native proto again to enable reads from clients when ready. Until then, make sure you’re using a consistency level appropriate for your requirements.