A raise on the river

I'm not sure I agree with this raise on the river.

The flop came 9h-8h-7s. Everyone checked and I checked.

The turn was the 6s. The small blind checked, the big blind bet $3. One other player and I called. $14.25 pot after rake.

The river was the 6h. The small blind bet $4. The other player folded, and it's my turn.

Our hero made it 12, the villian folded.

Read the post. There's a lot of explanation of why it's a good raise.

I'm not so sure about it myself.

Any thoughts?

Update:
One of the things I often forget to do is to write for the search engines. This post is about an online, nolimit holdem poker game. A low stakes poker game played on the internet. Just wanted to clarify that poker concept and comment on the strategy.