Is it unethical/unscientific to omit outlier data in a publication when they are in FAVOR of your argument?
Science aims at revelation and insight.  Before you can even consider dropping these samples, you need to understand why they exist.  

The reason is that unexpectedly "good" data can be just as much a sign of problems with your theory as unexpectedly bad data.  Are these data points telling you that you've got a bug in your algorithm?  Are they saying that the instrumentation you were using for timing was unreliable or not calibrated properly?  Or is it just that under certain circumstances your random problems happen to be exceedingly easy to solve?  There may be other possibilities as well.

If you can't determine why the outliers exist, then you must include them, in order to help the reader evaluate your work.  If you determine they exist for a problematic reason, then, well, you're not ready to publish yet.  If you determine they exist for a benign reason, then you can drop them from the figure, but you must explain exactly what you've done in the text and why, or else you risk misleading the reader.

At the end of the day, the data you got is the data you got, and you need to deal with it honestly.