This precedent can not allowed to stand. It is a direct attack against free speech and international sovereignty regardless of your affiliation.
* https://www.icao.int/pages/freedomsair.aspx
* https://en.wikipedia.org/wiki/Freedoms_of_the_air
Note that Belarus is not a signatory to the International Air Services Transit Agreement (IASTA):
* https://www.icao.int/secretariat/legal/list%20of%20parties/t...
Neither is Lithuania, but Greece is.
However, this most likely only furthers the goals of the current Belarusian administration for the population there. Enforced strictly, to include diplomatic flights, it may cause measurable change.