Grant took over at short notice after the surprise departure of Jose Mourinho last week but it has subsequently emerged he does not possess the UEFA Pro Licence required for him to manage in the Premier League.
He was subsequently given special dispensation by the Premier League to continue in charge at the Riverside on the understanding he continued to work towards earning the qualification.
"Avram is a very experienced coach and I think most of the older coaches were granted special dispensation when the rules were first introduced in this country," said Southgate.
"Obviously my views are coloured by my experience but I would think he falls into the same category.
"I am sure Avram has nothing to worry about because he has the backing of his chairman (Roman Abramovich)."