Actually I don't know the reason why you weren't here and really it's immaterial. That's not to sound cruel, because if you do have a good reason believe me, I'm sympathetic. If every "abandoned" home was left in place just because someone MIGHT be offline for a good reason, none of the abandoned structures would ever get cleared and the server map would be overloaded.
If the area was THAT important you should have known to protect it. If you know you're going to be away you should let someone in authority know that you're going to be away. If you are away and it's seeming to be a long time you can take 5 minutes to drop an E-Mail, forum message, etc. There are plenty of ways to let people know that you are going to be "absent" and your area should be preserved. Even hospitals (if god forbid you were in one) have public computers where I'm sure 5 minutes could have been spent to drop a message.
Trust me, I am sympathetic to people who loose areas because they had other priorities. That said, there are literally hundreds of people who come onto the server, build something, and never return. You can't expect the server hosts to hold your area if it's had no activity for a couple months, and you can't call it grief if someone has mod permission to build on land that seemed abandoned.
My original suggestion stands. Find another place to build, and next time you need to be absent let someone in authority know so your location has a better chance to be preserved.