He grew up in a Flemish foster family and was naturalized Belgian because of his merits as a member of the resistance during the Second World War.
Due to his experiences as a civil servant in Brussels, he felt the treatment of Flemings by the French speakers was unjust.
He was also an editor of several magazines and additionally made his point clear in speeches and letters he wrote to newspapers.
After his death, the Flemish community of Etterbeek – Brussels created a Foundation, called "Private Stichting Sändor Szondi".
The Foundation issues an annual award in cash to an individual, group or organization which has given proof of positive activity to the benefit of the Flemish community, living in Brussels.