This is true for our association, too. The Team Block feature seems to only block the actual time of a player's home game. It does not allow for travel time before or after the game, nor does it seem to block practices or tournaments. I'm not sure it even blocks the away games (I haven't got that figured out yet!). This creates situation where, even if the official has set a team block, he will show up as available for a game when he is not. Eg. the program would block his 8:00 game, but would show him as available for 7:00, even though he clearly wouldn't be. Louie's suggestion would help to solve this problem.
Another way to solve it would be to have officials enter when they ARE available instead of when they aren't. Then they would not have to worry about blocking all their games, etc. or their personal commitments. They would just let us know when they were available. If they didn't bother to do so, they just would never show up on the availability list and therefore would not get any games--good incentive to go in and tell when you are available. Currently, there is no incentive to set blocks, unless the association imposes penalties for denying or cancelling games.