There are hundreds of opportunities and many people doing it - either running training off their own back or contracted by host training organisations.
As always in this situation, it is a question of being known about, and having a proposition to offer such organisations.
Whether there is a market for basic 'business strategy' from this type of speaker, I doubt, because this is core to many training organisations offerings. What is more likely is that such organisations engage guest speakers to provide 'practical insight' and 'case study' type presentations to supplement the core topics of training / learning.
The best way forward would be to approach training organisations directly by phoning around. Seeing as he's been involved in selling, I'm sure this would be straightforward for him.