The ACT Government have called this the Molonglo River Reserve. That is official name. Please check the ACT government website. It is about zoning.
Thanks for the comment about PROPOSED. The cycle prefix would be useful. Similarly in the north there is a large are market "Whitlam". This is the new suburb.

A really interesting case.
A few points here.
1. your comment shows up as posted 6 months ago. But I got the email today. Sorry if I missed it early.
2. The MTB tracks on Mt Stromlo are managed company. They have some arrangement with the ACT government. Stromlo is part of a ACT Government master plan fot he area. The lastest development is a pool in the east corner. Where they want bikes is not my decision.
3. The general policy in the ACT are the formed trails can be ridden by bikes and fire trails are of that type. The trails on Stromlo are of an excellent quality.
4. The trail was originally market MTB=no. I questioned this with a OSM guy why that would be the case. I put it back in the end.
5. I simply dont know why this was done or if it was done for rendering reasons.

The question you should be asking yourself is did I change the river bank. The answer is no. The river banks where not edited.
The term "south bank" is a description of the are where the edits took place.
Becareful with the use of the word "blind" as it contains a number for assumption which you cannot verify.

A casual examination of fire trails (highway=track) on the east slopes of Mt Stromlo shows the tag “mtb” is rarely used but often the trails are tagged with bike=no. This is mostly likely an addition for routing. Garmin cycle computers, I have been told, love straight paths, which certainly MTB paths are not.

I welcome this. The ACT territory government has the policy that Mountain bike riding is permitted on formed trails including fire trails and shared use trails. This means that for highway=track that bike=yes unless designated otherwise. Fire trails (highway=track) of Mt Stromlo are permitted for biking however some are set to bike=no around MTB paths, e.g. the track that forms the junction of “Dingo” and “White Gums” MTB paths to the east of this one.