There are differing opinions on the wipe down method, mine was barely dusty at 35k, but for sure there's no place to ever spray or soak an electric throttle body. As for the service its a normal add on for them, I wonder if they actually do anything, cause a traditional soaking would be very bad. So if not it's it's $149 for a rag? It's just not kosher considering mopar says leave it alone.
The last thing at the bottom, credible source.
Jeep Grand Cherokee WK2 - Maintenance information and schedules