It looks like you can't use TYPE_SCROLL_INSENSITIVE and CONCUR_UPDATABLE at the same time on AS/400. The documentation says:

There is one situation where the application specifies a TYPE_SCROLL_INSENSITIVE, CONCUR_UPDATEABLE ResultSet. Insensitivity is implemented in the database engine by making a copy of the data. You are then not allowed to make updates through that copy to the underlying database. If you specify this combination, the driver changes the sensitivity to TYPE_SCROLL_SENSITIVE and create the warning indicating that your request has been changed.

Try using CONCUR_READ_ONLY.