Sitting out through blinds?

So today I was a guy sit out the hand where he was supposed to be the BB and sat out the next hand as well then posted when he became dealer. That got me thinking. Wouldn't he only have to post the BB when he joined back in? Therefore he is saving .5BB and not having to play OOP. Do the poker sites do something to protect against this happened??

The answer is not UB. I was just UTG and folded. I really did have to go to the bathroom and decided to sit out so I didn't slow down the game, while also testing this thought of mine. Well I came back in the next hand and sat in. Well instead of putting me in the SB, or on dealer position, the two guys to my left had to post the blinds, and the guy to my right was still dealer, and I didn't have to post a dead blind or anything. Here's the HH of that happening. Please explain or was that just a glitch/mistake in the software? And I'm wondering if that is exploited often or if I'm just missing something and it's normal.


Hand #49036802-41312 at Bridgewater (No Limit Hold'em)
Started at 21/Jan/08 23:28:17

crack_spackle is at seat 0 with $1.48.
LoStr8 is at seat 1 with $2.01. < That's me in seat one >
Herby77 is at seat 2 with $.72.
Carpe Mortem is at seat 3 with $4.56.
Jetzel is at seat 4 with $3.12.
gophergutswag is at seat 5 with $1.55.
Bigmanford08 is at seat 6 with $2.27.
DRILLUDEAD is at seat 7 with $.09.
BSmall is at seat 8 with $1.48.
mouthewash is at seat 9 with $.27.
The button is at seat 0.

Herby77 posts the small blind of $.01.
Carpe Mortem posts the big blind of $.02. < There's the two that posted>