Thank you ChicNot and welcome!
I'm not surprised either. Even though the government has no plans at the moment to ask the ex-Imperial branches... they haven't ruled it out completely. I bet if any ex-Imperial male descendant showed even the slightest willingness to return, the conservatives/LDP would do anything to get legislation though.
Some in Japan speculate Princess Mako's marriage dilemma will negativity affect proposals for female-led Imperial branches or even princesses representing after marriage. Kei Komuro is seen as an unsuitable connection. What if Aiko or Kako have problematic partners? Despite various opposition and mental health issues, commoners (only women so far) joining the Imperial family have been from the elite/privileged in Japan.
One farfetched theory on Japanese sites is the IHA or Akishino household leaked Mako's marriage plans and then authorized the media to scrutinize Komuro to prevent the marriage, a convoluted way to pressure the government about female-led Imperial branches. (Oh no, Mako's leaving. You don't want her to leave, right? Do something quick!)
The Imperial family/IHA also doesn't have experience with semi-private members. Either you're an Imperial member or not. What's a role for the husband of a princess?
Despite the IHA making a few baby announcements regarding Ayako Moriya, she's been left alone as a private citizen.