This is such a long, ranting post of drivel that my phone was unable to cope with it!
Basically, the above blogger is too "pure" an aroace to understand that some aros and aces might feel attraction once in a while. Some might experience it a few times a year and others might only experience it once every twenty years. The "expert" above thinks that either way, they cannot be A-spec.
See the grey in the flags? The grey in the A-spec flags has been put there for the greys -- demis included. Because all attraction is a spectrum. I have listened to M-spec (bi, pan, etc.) people say they are more attracted to one gender than another but are still attracted to more than one gender, thus M-spec.
Finally, gatekeeping the LGBTQ+ Community is rot. To gatekeep our own community, when exclusionists are doing exactly the same thing to us is even worse.
If you cannot relate to a grey ace, a grey aro or an angled aroace, either try listening to them or walk away. Long, ranting posts like the piffle I have just attempted to use as an example will just make you look arrogant and foolish.