No, since the claim "veganism does cause intellectual deficiencies" is still wrong, because veganism doesn't cause this, a lack of supplementation does. And most vegans supplement adequately. So saying that veganism "per default" causes this would be dishonest, because it implies that not properly supplementing is the default/intrinsic to veganism, which is not the case.
It's like saying "drinking alcohol kills you" just because you have to be mindful of limiting your consumption and it can kill you if you don't. An extreme statement that contains a kernel of truth, but is simply not correct.
In regards to the memory training: have you double-checked how much Ram your CPU actually supports, at what frequencies? For example even the 7950X3D supports only DDR5-3600 when you put more than 2 bars of ram in, leading to issues with memory training taking long/not posting/instability if you enable any form of overclocking in that scenario. I had that problem before and switching from 4 bars to two fixed everything. Just in case this might be your issue as well.