I may be missing something here, but the article seems to say that they have refused tribunal requests to change the points awarded for distress when travelling and needing prompting etc to take medication. I couldn't find anything that says they're changing existing regulations.
"Do I assume that people with variable conditions just can't claim PIP because on some days they don't score enough points?"
If they are affected by their condition for more than 50% of the time, they're still entitled to those points. At assessment, they are invariably asked how many days a week they can't do this, that or the other. Say 3, they lose those points, say 4, and they get them.
I have won appeals with clients with uncontrolled epilepsy by establishing the point that, because the risk of a seizure is ever-present, they can never cook, bathe, travel unaccompanied etc. I've also used the difficulties people suffer when in a post-ictal state, eg extreme drowsiness, disorientation etc and succeeded in having points awarded for communication etc.
The real problem with PIP (and ESA) is that the questions don't really reflect the regulations, so people aren't likely to give answers that will help them get the best results. No-one should ever complete the forms without reference to the "descriptors" and the regulation that says you can't do something unless you can do it safely, reliably, repeatedly and in a reasonable timescale.
Plus, of course, cutting the Legal Services Commission funding that used to keep lots of benefit advisers in jobs, so people could get help with the forms.