Would this be a good play for an elementary school to do?

You would first have to contact the copyright holder to find out if you can get rights to do the play. If the copyright holder says yes, then you would have to find out the cost of the royalties. Find out if your school district has a blanket license to do any play.  

I don’t believe anyone has written a play for The Flintstones.  There are not enough characters. Elementary school plays try to get as many kids involved as they can 

What size is the budget and who will be the actors?  You need people who can memorize the lines and business and creative people who can make the props and costumes.

I have no problem with Betty and Wilma being housewives  Most women do housework  It is no shame. My mother  volunteered to run a charity/second-hand store when we were grown up enough to help with housework. My sister-in-law teaches piano as well as do some - almost all? - of the housework. My nieces shared a part-time child-minder before Covid-19  She minded in her own home. Now one works from home and sometimes has all four kids.  Besides Wilma and Betty can get jobs and make sure their husbands share the load at home.  The play can be a learning experience. The Simpsons live in a  multicultural neighborhood.The Flintstones were confronted with 'differece' when the Grusomes became neighbours.

It was moron-level crap on tv - we shouldn't teach kiddies to be that stoopid - as you well know.

I think it wouldn't work. There would need to be a lot of movement for it to succeed, as this was where much of the humour in the cartoon came from and a stage play would be far too static.

No. Absolutely not.  The Flintstones are white and have no minority characters at all.  Fred sometimes raises his voice to Wilma, a suburban housewife who  seems content to be supported and either lacks ambition or has had no opportunity to express her abilities and work for fulfillment.   Then there is the animal abuse where pets are used as household appliances, many times complaining about the abuse as when Wilma pushes open a pterodactyl's mouth to drop in the household garbage.  The bird painfully looks into the camera, breaking the forth wall and sadly says, "It's a living".  There is apparently child abuse next door where neighbors Barnie and Betty encourage their baby to beat and smash things, even naming the child BamBam.  No in todays PC environment where children are only allowed to think along predetermined PC curriculum the Flintstones might encourage them to use imaginations  They might even become interested in learning about the past and government approved researchers have not yet rewritten history that far back into the past.  The Flintstones must not be considered a good choice for youngers to be exposed to.   If I've not convinced you yet, here is a tidbit of information which should do it.  The Flintstones during part of their network run on ABC were sponsored by Winston cigarettes. True.  In the early days the characters were depicted smoking cigarettes in sponsorship mentions.  Nothing a white man has done in the past, whether 200 or 20,000 years ago is to be forgotten today and the Flintostones were smokers.   You should not only ban the play but you should encourage students to go home and demand restitution from parents who may have watched the program.  

yeah, that could be really cute and funny. go for it! (watch all the episodes and use an appropriate one). get good artists and crafters to make the background; boulders, Jurassic sized plants, and the animal appliances and machines will be fun!)