
Autism is a syndrome characterised by symptoms such as problems with social interaction and communication, as well as repetitive behaviour and restricted interests.
The problems (if one can call it a problem at all) one have vary from individual to individual, and the way these traits are expressed also vary, but those are the basic characteristics.

I am just wondering if a person who really has a different sense of value compared to the general people and very uptight about it is considered being autistic? Serious question with no sarcasm or offemse at all.
I'm just thinking like will it be possible that like the manga is portraying since it's not outright saying he's autistic hat ge really just have a different sense of value and that's not being autism at all. like that's how your philosophy is and you won't adjust to everyone just to cater them... or something. like you're not really having a hard time interacting you just don't want to cater them or something... or that's exactly being autistic is?

Being eccentric isn't the same as being autistic, but many autists are seen as eccentric. The reason why it's so probable that this character has a diagnosis within the autism spectrum is not that he has different values, but the way this is shown through his behaviour. The way he doesn't know how to judge what behaviour is appropriate in different social settings (the character acts the same in all settings, he doesn't change the way he acts based on the situation). The way he himself doesn't realize how he's perceived by the others, and how he doesn't intuitively know when to use what social norm (saying "itadakimasu" or the like in the restaurant, or trying to pay the mc at home).
Well, more than that: a syndrome is a collection of symptoms. So if you have just one of the symptoms, you don't fall as easly into the category, but if you have several of the symptoms it's much more likely that you will be diagnosed with that syndrome. This character doesn't just only have one of the symptoms: social awkwardness, communication problems, repetitive behaviour and restricted interests; he has them all. That makes the diagnosis more likely.

I think, based on what we have seen so far, that he have a slight autistic syndrome, the Apesberger syndrome it's similar to my nephew, they seem very normal on the outside but they have communication problems, sometimes they talk and comunicate with others normally ,but sometimes they have some little obsession such as like and dislike they 're very fixated (the character so far with carrots, my nephew with onions, or Justin Bieber he hates him very much!) Often, sadly ,people don't realise that they have problem with comunication and end up arguing very often...
in the simplest way, what exactly is autism?
i think people like tatsumi are cuties. like they’re big kids that’s learning. i mean, no matter how old you get, we’re still learning but i specifically love stories (and real life cases) where the love interest takes lessons from the main charatcer and warms up to them.