Breaking it down like the law? No, just trying to understand what they are saying.No need to break down the wording like it's the law. IRCC is simply instructing visa offices to to consider that most applicants with visas that are expiring in the next few weeks will not be able to travel. When identified (mostly through web forms), those approved PR visas can be extended for an additional 6 months without the need for another medical exam or police certificates.
You are correct in saying that they are identifying applicants whose medicals are about to expire. However, it says medicals expiring in the coming 4 to 8 weeks. This is the part that is less clear to me.
If you feel like I am being pedantic, then you should look back a couple of weeks. Everyone and myself included were overjoyed by IRCC adding 'or unwilling' in their program delivery. Yes, two words made a world of difference.