The user created new table under the SA binding to backup the table of solution,
but seems that the router purged the expired events in this table also.
The User wants to make sure it is true that our router will purge all expired
events under SA datasources,no matter it is a table created by solution or by himself

That is right . The Router delete expired events of all tables that have a changes file format defined in the SA datasource. To backup tables, they should create the tables in a separate datasource