Build a "default menu block" to show a menu by path, rather than menu item

Background
My drupal site has lots of menu items created by views pages (e.g. "/events" and "/news").
The views show nodes of a particular type (e.g. "Events" and "News").
The nodes are not menu items (and I don't want them to be).
But, the nodes share a common path (e.g. "/events/awesome-event-1" and "/news/breaking-news-item").

Problem
If I set up a menu block to follow the active menu item, the menu context is lost when I get to a node.
ie. since there is no active menu item, the menu block shows the top-most menu.
I want my subnavigation menu to appear contextually for nodes whose paths match a menu item.
e.g. when i'm looking at an Event node, I want to see all the menu items under "/events".

I know this can be done by mechanically creating a new menu block for every section, and assigning it by path in block settings.
However, this is tedious and unsustainable - I would like a single block that takes care of this.

Solution
I created a "default nav" block based on 2nd-level primary navigation.
I created the attached module that implements hook_menu_block_tree_alter().
My hook_menu_block_tree_alter() implementation searches the menu tree for a menu item with a path that matches the request path, as described above.

It's not perfect, but it gets the job done for me.
I hope it will help someone else.

I'm posting this as a feature request because I think it could be useful as a configuration option for menu_blocks.
Though this attachment isn't a patch, but a proof of concept implemented as a third-party module.
If other folks would benefit from such a feature, I'd be happy to make it into a patch.
There are some inefficiencies built into this module which could probably be solved by patching (or duplicating effort from) menu_block module.