When Topology Publishing is implemented then only we faced this new issue. Before that it was working good. When Author go to Activities Panel, Select any Bundle workflow assigned to him and to try edit the page then its forcing the Author to edit page using Experience Manager only. This means now Author can not edit the page if experience manager is not installed. Its a big issue for Author and should be fixed on priority. It should launch the page editing by default in CME as it was working before in CME.
SDL Ticket 00632881