What does it mean to "legitimize" someone by...?

[o snap]

I'm facebook friends with someone who always posts political stuff. But a lot of their posts are things that are retarded. I can disagree with someone while respecting them, but this person is very easily misled by half the things they say/post.

I sometimes comment trying to 'open their eyes' or point them in the right direction, but most of the time it just leads to them saying more ridiculous things. One of my friends said "oh dont even say anything, dont legitimize this person by commenting.. just let them be."

[New York, New York]

in a classroom of 30, there's always one weirdo, you may not know who . When they get home they come to Yahoo answers. If every weirdo in the world does that, that's basically everyone on Yahoo Answers.

[Bacon]

To encourage them or egg them on in their thoughts/opinions.

If everyone ignores them, their thoughts won't be justified with a response. But if you do respond to them and give them any time or attention for their bogus comments, you give them what they want.

It is more fun to watch the idiotic political posts on Facebook just go unresponded to.