I'm not sure I see bias here. The statement is certainly true. Though one could argue the "ideological" bit.
The Persians were certainly tyrannical. The Greeks were certainly in most cases a "freedom loving" democracy for their own people. Both sides took and kept slaves. The Persians were sightly less genocidal than the Greeks... who had no trouble wiping out foreign peoples and cultures. The polyglot nature of the Persian Empire and Cyrus' example did tend to mitigate their worst tendencies. Though of course we have ample stories of the Persians willing to wipe out peoples with little encouragement.
Perhaps the real bias here is for us to equate Empire with evil and freedom loving democracy with good. Both governmental forms have certainly produced abundant amounts of both...
The ancients did what they did according to their laws, customs, religious beliefs and level of understanding of the physical world. It's not their fault that some later people glorified them. A bit harsh to judge them with a modern eye? But in reference to the original post, it was the Persians that started it after all. Over a bit of earth and water as a sign of submission.
PS Heaven forbid that rich and influential families influence modern day politics...