TL;DR: likely because demand was too low to sustain commercial distribution
Barring any relationship to a specific historical incident, it's very difficult to find out why a specific food is no longer commercially produced. In the absence of specific reasons, we can see a number of contributing factors as to why grape preserves would have gone off the ...
I received the following response from Bonne Maman in France
Dear Mr. XXX,
Thank you for contacting Bonne Maman®. We are always happy to hear
from our consumers. You are the reason Bonne Maman is such a
Bonne Maman is owned by Andros SNC, a privately owned, family run
company, situated in the southwest of France. Our ...
It could also possibly be because the modern varieties of grapes commercially grown for eating do not make a good jelly or jam.
Having made jam with a variety of grapes I have found that most of the grapes we buy as table grapes make a fairly ordinary jam whereas if you can get hold of older cultivars, grape jam/jelly is an amazing preserve.
For what it is worth, in case you want to make your own grape jam.
The recipe calls for basically four things: grapes, sugar, lemon, butter. And as I have gotten a lot of recipes off of SeriousEats.com, I figure this might be worth a look.
Check it out here.