It isn't obvious that the SSW program itself is designed with abuse as an intended outcome. I also don't get the strong sense that these changes to the PR process, at least what actual documentation is on https://www.moj.go.jp, are going to have much real impact other than prompting those with a real long term commitment to life in Japan to look more closely at the naturalisation process and possibly motivate SSW1 workers to be more serious about upskill to SSW2.
Because SSW1 time no longer applies to the 10 year PR eligibility (which can be shorter with "contribution to Japanese society" https://www.moj.go.jp/isa/content/930003503.pdf), this makes staying at SSW1 for longer than 2-3 years a bit wasteful if the goal is PR.
Perhaps there is some room in this system for well-managed RSOs to take a more active role in helping current SSW1 employees take the necessary steps to prepare for transition to SSW2 and perhaps this kind of action is something that rural townships should look at as a mechanism to improve their local workforce options.
I wonder if there's any employers in your extended network who could gain from having access to workers already holding SSW1 visas with 2+ year remaining on visa and helping prepare those workers for SSW2 testing and retention along with long-term work contracts. It would seem to be a real opportunity for companies struggling to meet production objectives due to labor shortages without the potentially high initial capital cost of finding those workers from abroad and the cost of turnover and training that come from short term new workers.
I'm just kinda thinking out loud here; it seems to me that where there are avenues for abuse which appear to offer little recourse for the workers, then there may be an avenue to offer that recourse and in turn benefit from the ready capability and earned loyalty of those workers. Sure, your bed-pan example is a worst case job scenario, but that field of SSW is not restricted to only bed-pan level work, and surely there are companies who need quite a range of ready workforce for many tasks that would fit the same visa which can pay a decent wage for skilled labor which are not 'black companies'.
I'll try to introduce some of this into the discussions at my next informal soudan kikai. The shiyakusho team heree has been great at facilitating the network of contacts and interested parties which has enabled our current opportunities, and been very involved in every step from the moment we showed interest in living out here in the 'inaka'.