The quote in the tweet is a distinction without a difference, for one.

It's a bit like telling a permanent wheelchair user that they're not too disabled to get out and about but if there are no accessible public transport services and they can't use a car then, yeah, they are too disabled to get out and about.

The cause of the disability can be debated but the reality of the disability doesn't care one bit for how you make that distinction, as you have already argued.

Secondly, autism is pretty well known for being a spectrum and you can't universalise the experience of autism just because Ellie in IT is autistic and she copes just fine (Does she really though? Is she so burnt out that she has zero social contact outside of work? Is the rest of her life a complete disaster? Does she literally spend each weekend stuck in bed as she tries to recuperate enough for the coming work week? You can't know what other people are going through unless you really know them.)

Third, autistic people have a high rate of catatonic episodes compared to most other populations. If you're autistic and you experience catatonia then, unless your job is a one-in-a-million with regards to accommodations, you're either going to be unemployable or you're going to bounce from job to job as your resume looks increasingly poor and you lose references and you dig yourself deeper and deeper into burnout.

As for your friend who doesn't believe in spoon theory that's simply an expression of their own personal experience being universalised onto everyone. If you've ever experienced burnout or you've been through it yourself then it's pretty obvious that you can push through but that it comes at a high cost and ultimately, at some point, you won't be able to continue pushing through.

I experience pretty severe bouts of executive dysfunction (hooray for being autistic and ADHD, I guess?) and there's a point where I get to that I just have to drop out of activities and recuperate. I can push through but I'll start losing possessions like my cards, my wallet, my keys, and it can even get so bad that I struggle with basic directions and following simple instructions and I'll forget to do things like locking things up, taking important things with me, or turning the oven or the stove off.

Can I push through? Of course.

Do the consequences of pushing through far outweigh the minimal benefits I might get from pushing through? Absolutely.

Just because you can do something doesn't mean that it's healthy, sustainable, positive, or that you should do it (and especially not on a regular basis.)

Can you go out drinking all night and then work the next day? Sure!

Can you do that every day of the week? Maybe...

Are you going to keep your job if you do that for longer than a week? Probably not.

I'd love to hear what the spoon theory-skeptic would have to say about "pushing through" on a week-long bender while trying to hold down a job. But that would probably come off as picking a fight so I doubt it would be worth the discussion.