I understand where you are comming from but
“compatible with the Arduino software”
is true, what it does not do is allow user hacked code to run without modification but then it didn't run with the Arduino software until someone wrote code to allow it to. I'm sure the people that decide to use the Sanguino will port any code they see as useful in time. I would like it to run all code out of the box but since it is a different animal I can see why it doesn't.