Well you learn something new every day.....such is aviation.
......I'll have to check the POH again, but if its only a recommended procedure then its hardly critical to start faffing with flaps during the landing roll.
I'd be interested to know the difference in landing distance between the two techniques??
It was also never part of my standardisation or even in the company training manual to teach flap retraction on touchdown. Personally, I think there is more benefit of drag flap during the landing roll out unless it drastically reduces your landing distance.