Maybe I’m more trusting, but I don’t find this particularly nefarious. He could well have been babysitting her and putting in an hour of proselytizing before taking her to a fun activity.
On the other hand, I would not have been please to have someone knocking loudly on my door before 9 on a Saturday morning. In any case, my community has an anti-soliciting bylaw so such activity wouldn’t be officially allowed, although in my experience most people ignore that and simply say “Sorry, not interested.”
ETA another thought…I think Jehovah’s Witnesses are supposed to door knock in pairs. I think it has to do with Jesus sending the apostles out in pairs. This may have been an attempt to remain within the letter of the rules if he couldn’t find an adult partner to go with him. Probably not the most fun activity for a small child, but then again I didn’t find going to church particularly fun and I did that with regularity all through my childhood.