As a guest, you are allowed to download the file. You can do
this either by double clicking or by selecting the file and
clicking on 'Save Selected File'. But you can upload or delete a
file only if you have a host or presenter role ( i.e. userole 50 or
FileShare Pod is added in the example LoginDialog.
The 'Save Selected File' button is enabled only when you
select a uploaded file ( be it for user or for host/publisher).
When you go into a room as a user , it will be disabled by
default , but if you single click on any uploaded file and select
it, you will see it enabled.
Yes caching could be one option.
But here it seems you have autopromote=true turned on for
your room. So, any user who comes in as guest is getting
autopromoted to presenter role and is getting all controls. You can
change this property either through dev console by logging into
your room or through programmatically in your application by
LoginDialog.mxml actually has code that sets autopromote=true
and so you are seeing full control when you are going in as guest
since you are getting promoted to presenter role.