One of the editors on TVTropes suggested the 'Jim trapped in his own body' storyline was meant to function as a useful reminder of how we all-too-often treat the elderly and/or disabled. And I guess that's one way of reading it.
But honestly? Not buying it for a second, here @ Shoe Central. By this phase of the strip, we were deep into Pattersaint territory, as confirmed by the literally nausea-inducing number of 'Mike the Sensitive Genius' strips I had to wade through to find this one. Other hilights include Mike using his 'extraordinary' talent to smugly inflict petty revenge on the Kelpfroths; Mike smugly throwing his in-laws out of the house, while Dee looks on doe-eyed at such a masterful display of masterfulness; and oh yes, Mike self-centredly abandoning his family on a fire escape to go back for his laptop...
*pause while I work generalised hatred for smug self-centred Mike out of my system enough to continue*
...OK, right, Grandpa Jim's stroke. Then the next one. Then the heart attack. If a Very Special Episode about eldercare was the intent, I could see Lynn writing all this as the Pattersaints fighting nobly for their fallen patriarch against the indifference of the medical system. Or perhaps their trying to cope with him themselves, and patting themselves all over their anatomy for the wonderful strides their love was enabling him to make.
But the storyline as it stands, as exemplified by the strip above... that's just cold. Forget that this is Grandpa and you'd think he'd want to find out exactly what's going on and what he could do to help; let's just take this as a visit to Joe Random Guy, and It still hits me in the gut every time I think about it: Mike the incredibly sensitive, empathetic, whatever else his publisher called him, can't understand that elderly people who have just suffered massive brain trauma might be less than lucid. Nor even that it might be rude to talk about people like they're not there, let alone sick people, let alone call them crazy. Damn.
And it's not just Mike, either. None of the Pattersaints are shown caring any more for Jim than they would for a random neighbor -- except April, but she's a kid and kids are supposed to be all mushy over their grampas 'cause they don't know any better, right? The adults, on the other hand, react more 'maturely' -- they let an equally elderly woman handle the brunt of Jim's care, and maybe bring him a casserole every now and then. As you do, for your sick neighbors. They show no desire to reach him, not even in their random body language (there's another, later strip that shows Elly standing casually around watching her father be miserably depressed).
Nowhere is it more scarily illustrated: in the Patterworld, people who suffer are expected to be silent. To suck it up and consider how they're making it tough on the people around them.
Even if they're eighty-odd. Even if they're being miserably humiliated. Even if it's obvious that they've been reduced to only being given attention when it makes their family feel good about themselves (cf. Elizabeth and the idiotic wedding-dress demo, also Heroic Elly heroically coping with the cranky ol'guy for a whole week).
Combine that with Lynn's admission that she felt nothing when her parents died, that their strip avatars were a way of working through that, and there's a disturbing undercurrent of '...and I must scream' about the whole thing. Oh, what the hell, there's no undercurrent about it, is there? This is Lynn torturing her father, isn't it? Gleefully. Over several years. Complete with his children making stupid puns for a capper.