This is more of a priming of the plant against attack, so this is not really SAR but the molecular basis of systemic resistance (ISR) induced by T. hamatum
Trichoderma are well known for their capacity to stimulate plant growth and development, as well as their ability to increase plant tolerance to abiotic and biotic stress.
But this does modulate the same pathways as SAR but goes about it in a different way.
And yes, it is still a form of stress.
Also Phytohormones like Auxin are also produced and they stimulate growth.
https://apsjournals.apsnet.org/doi/10.1094/PHYTO-07-18-0218-RVW
More on stress here.