It fits with the long discussion we had on this question :
What is the connection between quantum optical photons and particle physics' photons?
and the answers and comments therein.
People working with quantum optics have a more general view of the term "excitations of the electromagnetic field". In the quantum field theory used in the standard model of particle physics, QED for electromagnetism, there is a single excitation of the electromagnetic field, called the photon field , which is the photon in the table. It is a zero mass, point particle with spin +/-1 and energy=hnu, where nu is the frequency of the classical electromagnetic wave built up by photons of this energy.
Quantum optics physicists use a generalized quantum field theory, which coincides with the particle QED when in vacuum. Classical light in matter has quantum behavior that can be described by a field theory, and they call the excitation of the field they use, photons.
This is what the sentence you quote:
Light is an excitation of the electromagnetic field, with photons being the lowest energy excitation.
implies. I would say the professor is a quantum optics physicist.