Is it true saying “no” to a child with autism is wrong?

No. Thats just stupid.

The world is literally on fire today because of weak parents that never said NO

It's possible, but you may have to explain to them exactly why they can't get their way... That's how my mom did it with me.

All I knew was that I wanted something and I wasn't getting it, but if she'd calmly explain WHY I couldn't have something instead of yelling at me or going for the paddle/timeout route - that generally kept me from having tantrums and I was mostly agreeable, if a little pouty for a few minutes...

That is the biggest bunch of bullshit ever, she  DOESN'T WANT to say no, so lets him have whatever he want cause she DOESN'T WANT to deal with his meltdowns.  At some he is going to want something dangerous, what is she going to do then.  We ALL have to deal with not getting what we want even Autistic children or people, they just have a harder time dealing with it I guess.

the largest problem with special ed kids is no special ed education for parents. no parenting classes to guide, assist and direct and educate parents on how to effectively work, deal and teach children.

offen parents pacify verses working through the situation.

id just meet at the park.

I think you should listen to your friend's requests about putting certain toys away, because she has likely learned the hard way that those kinds of toys are meltdown triggers. A tantrum is one thing, every kid goes through a tantrum phase, but meltdowns are a whole other ballgame. 

Putting away overstimulating toys is really not a big deal, I've done it a few times for an ADULT parent friend with Asperger's who finds electronic toys very grating. There are still plenty of toys for kids to play with after you've put the noisy, flashy, music-making ones away. If you're not comfortable with this, then suggest to your friend that you meet up with her and her son somewhere else instead.

Any kid, autism or not, who doesn't learn he or she can't have everything they want and never hears the word "no" will be a very difficult child to deal with. 

It isn't so much about being "wrong" - it is about how it just won't always work.  They process things differently and just being told "no - you can't have that" results in a melt-down because they can't process their emotions to handle not getting what they want.

There are various distraction techniques to try to deal with these issues and some autistic children are more severe than others with respect to how badly their melt-downs will be if they don't have what they want.  This parent should be working with her child and a therapist for methods on how to deal with disappointments and how to deal with it when she does need to stop him from doing something.  Never saying "no" to anything is not a realistic option.  Personally, I think she needs to find a better therapist to work with her and her child.  (and if she is not in therapy with her child - that needs to happen - parents need to learn how to deal with their child's autism - it isn't just about sending the child for help)

Just to put things into perspective.  Imagine the worst emotion you have ever experienced.  Maybe it was extreme anger or maybe it was extreme disappointment or sorrow.  Now - imagine being stuck in that emotion and you can't calm yourself at all.  You are completely stuck in that worst moment because you don't know how to deal with emotions.  This is part of what some autistic children go through.  They often get stuck in an extreme emotion and can't deal with it.  And just trying "discipline" also doesn't work.  Then they are stuck between two extreme emotions.  The parent needs to learn how to calm their autistic child without always just giving in.  The methods for discipline that work on other children usually won't work on most autistic children.

Not every form of autism causes these kinds of issues.  There are many levels to autism and many types of autism.  Some children have such mild autism that it is barely noticeable while other children have extreme cases and it can be hard to manage.

No. All children need boundaries. Even autistic ones. She's not teaching him how to get along in the world. Autistic children can learn.  

I saw this severely autistic kid at a Best Buy and his father tried everything he could to get the kid not to open blu-ray movies but he refuses. He would cry, throw a temper tantrum. So the dad let him open a few boxes then carried him away. 

It’s easier to just hide stuff. Once they become fixated on an object there’s no easy way to get him to leave the item alone.