No it won't, that's a really odd take. Perhaps if you want a job in very specific sub-section of cyber-espionage stuff, you might have a problem with existing on social media (although I doubt it)

But the idea that general IT security companies have a reduced chance of hiring someone based on their information being on social media is... not the case.

Nope, sorry, this isn't accurate at all.

That's a very odd thing to say. There are so many security professionals in the world with LinkedIn profiles.

This is not true.