The point about force behind a palm strike vs. a punch - that really depends on how that force is being measured. (Disclaimer: I haven't looked at the provided link...)
If it's simply 'weight behind it' then they're likely to be very close, and if you're measuring 'knockout power' based on a random placement on the head there's not much in it. That's because the actual weapon becomes the skull against the brain.
Anywhere else though, it's different. A palm to the ribs will spread the force from the strike over multiple ribs because you're dealing with maybe 6 square inches. A punch of the same force though, that's down to 2 square inches, so the force over area is 3 times greater.
Here's a very extreme example - get a hypodermic needle and measure the force required to pierce skin. Now get a brick and apply the same force (you'll have to support the majority of the brick's weight) - does the brick break the skin?
The area over which the force is applied is instrumental in assessing how much damage anything can cause.
I think pdg has a good point about identifying those who aren't good fist strikers from those who aren't good slappers and teach them what will work best for them. Even identifying which students are which will take more class time, but I think would pay off for the students in the long run
At MOST this will be a whopping 16 hour course over days. Perhaps as short as 8-10 compressed into 2 days. It's all about time management
If someone is an instinctive slap wielder you won't convert them to punching even if you spend the whole 16 hours on that single subject.
The inverse is also true though, my sister (who has had no training whatsoever, never even an hour sd "class") is an instinctive puncher. If she was to attend a short course where she was compelled to palm it wouldn't work. At best, in a stress situation, it would be forgotten and she'd punch - at worst though, it'd make her question her instinct ("but I've been told that's wrong") and that delay might stop her getting any strike in at all. When does a good intention become a disservice?
Considering (what I assume to be) the nature of this course, you're not doing it as a striking lesson. I imagine you should be covering situational awareness, de-escalation and all the other buzzwords - so you'll have a couple of hours left for the physical side.
Personally, I'd start the striking portion with "hit this pad", and see how they do it...