Where the lack of empathy is concerned, obviously people just don't understand how difficult something can be on an extreme end of the spectrum, and that's why we often get the uninformed suggestions that some sort of discipline will help solve the problem. Which I can't be too upset about it, as I labored under similar misconceptions until I had direct experience.
I may suggest one thing we did to start removing certain things so the lack of the target item is less critical:
Find more things your child likes to line up. We have PlusPlus [0], LEGO, Tegu [1], and wooden train track [2] available. Once you have a variety of options removing one of them is less likely to cause a meltdown if they've started using the others. This dilution of the importance of something they are attached to has been amazingly helpful.
Note that for TEGU and PlusPlus they can occasionally be found (typically after Christmas) in the discount stores (TJ Maxx, Marshalls, etc.) for huge discounts if you are in the USA. Otherwise shop around.
[0]: https://tegu.com/
[2]: https://www.ikea.com/us/en/p/lillabo-50-piece-track-set-1032...
As a parent of an autistic child who fights similar battles I feel for this person. I can’t put words in peoples mouths, so here’s my own interpretation:
This person more than likely knows this isn’t the right answer but is at their wits end and looking for the least damaging option. Rather than berating them for something they likely know is bad please realize this is the tip of an iceberg and they are quite possibly in damage control mode. Some of the comments here (like the chewable necklace) are great. Others (the many who are berating the parent for even considering this) missed the larger issue at play.
OP: We deal with similar things and we’ve found wooden toys to be the best alternative. Our son used to love the silicone chew toys but now wants something better so we seek out US/EU made and well regarded (from a chemical perspective) wooden toys so that if he does chew it doesn’t hurt him. There are some things that are just a forever fight to keep away from him. Specifically for batteries he doesn’t touch them now because he associates them with being needed for his Leap Pad so that’s a higher priority for him, so creating a higher need like that is a possible way as well.