Not sure if you have found the solution. I had a similar issue and resolved it easily.
Locate the view in which the ROADMAP UI element is located. e.g. for FPM_GAF_COMPONENT it is the CNR_VIEW.
Make a not of the ID of the Roadmap UI element.
In the WDDOMODIFYVIEW implement the Post Exit Method get the roadmap ui element which is of type CL_WD_ROAD_MAP.
Call the SET_ON_SELECT method and set its value to blank i.e. ' '.
This will ensure that there is no action set for the onSelect property of the UI element and hence we will not be able to navigate by clicking the road map steps.