I believe some MSG is still made with this and causes migraines and other heart issues, it's mostly phased out though, and can cause mixed reactions as the type of MSG isn't labelled, let alone MSG.
Until you can provide a shred of evidence for that I will assume you're just adding a layer of legitimate-sounding abstraction to the same superstition. Toxic precursors =/= toxic end products. This is chemistry, not alchemy.
Your link has no mention of the subject being directly used to manufacture MSG, and only mention a link to glutamic acid being used for syntheses of it. This is not adequate evidence that Acrylonitrile was ever present in commercial MSG.
I believe some MSG is still made with this and causes migraines and other heart issues, it's mostly phased out though, and can cause mixed reactions as the type of MSG isn't labelled, let alone MSG.