Ethics in online poker?

Sorry I haven't written much lately. I'm in the middle of a downswing and there simply have not been any interesting hands. Poker Meister was cracked for the first time in awhile, yesterday, but for very little money. Outside of that, nothing else interesting. I get out-flopped, out-setted, sucked out, etc. The last statement is fairly typical for a downswing, and I've become somewhat callused to the chain of events. The saving grace is the "it'll even out in the long run," and "my upswings are way more EV+ than my downswings are EV-." Perhaps that's a loser's motto, but so far, it's proven true...

At any rate, the point of this post was to discuss ethics in online poker. A few times [a month?] I run into situations where [action or no action pre-flop] my opponent will let his time meter run down to the end and the computer forces an insta-check. I am very aware of this situation, and the poker client software will essentially put the player into a "check / fold to any bet" mode. Being the aware player that I am, I immediately take note of this player and min bet the first second I can, thus forcing my opponent to involuntarily fold, and allowing me to scoop the pot (assuming we are heads up). The question I have is this: Is this ethical behavior?

I, myself, justify it by thinking that this player has other problems or issues going on, and should not be playing at the table. I should not be hampered by his inaction. If he is multi-tabling, perhaps he should not. If he is multi-tasking (other than poker), perhaps he should not. Clearly, he is not disconnected from the internet; there are different rules from the poker client software regarding disconnects. To end: This is a game of mistakes. I capitalize on my opponents mistakes, just as the reciprocal holds. Letting your timer time out is a mistake, and I should and will continue to capitalize on stealing those pots for a song (or in this case, a min bet).