I am pretty certain that this is by design, since V2 works in the same manner.
This said, I find that both ordering are useful sometimes, and since there are two places where they are displayed in different orders, I am guessing that the relevant entries in the database tables are indexed for speedy retrieval.
If my guess is true, it should be easy to add a control to sort the topics by either criterion. There is definitely enough space to put a sorter control in the gray bar above the activity list or in the forum page.
On a club's home page, forum posts (the "Activity" pane) are ordered by post origin time. On the club's forum page, they are ordered by last comment time (a much more useful ordering).
Actual: Home-page "Activity" pane listing is ordered by post origin time (and the originator's name is displayed).
Expected: The home-page "Activity" pane ordering should be by last comment time (and the last commenter's name should be displayed).