I think it likely that this move is an effort to remove the gap between premiums paid on behalf of dependants and when young adults re-join before the lifetime cover limit. There are many young people deserting the system during that interval.
This graph shows the problem:
https://choice.community/uploads/default/original/2X/0/011f70a9c056b3973582e0287bcf88c24f9058a7.jpeg
To catch up with the wider issues have a look at the thread on Fix private health insurance
