I agree, but that's only because we're anti-Man Utd and/or the decision hasn't gone against us. If that offside was given against Man Utd rather than Coventry, there'd be so much less sympathy.
The main issue for me is that I'm not sure how they've determined he's factually offside. Weirdly, the player looked more offside without the lines being drawn than he did when they were drawn.
I don't know what the answer is, if I'm honest. The new system is a mile better so that should help, but there's always going to be horrifically tiny, marginal calls which get given as offside/onside.