Flash Memory Floating Gates and heavy ions causing bit flipping

Hello!
I'm always thought what flash does not have radiation hardened capabilities cause they have got floating gate what can be switched by heavy ion

But, according to page 36 NASAs reporters maintain what configuration of ProASIC3 is already hardened by nature.

https://www.inaoep.mx/seressa2015/archivos/Jueves_11_00_BERG.pdf

Can somebody explain, please, does it has an some acknowledge? Thanks in advance!

I think what they are saying is that flash-based FPGAs are harder than SRAM-based devices, not that they are completely immune to SEUs. But it's a long presentation and I may have missed the point.

Yes, I thought so at the beginning but after searching another similar sources I found the same declaration.
That's why I decided to clarify physics basis in this case from this source.