Would someone with a phenomenal memory like "Rain Man" be able to learn languages faster?

The real Rain Man, Kim Peek, spent time in libraries and could tell you all the facts he learned by memory. If he just read through a phrasebook or dictionary, is it also possible he could just recite all the words and scripts of a foreign language?

https://www.youtube.com/watch?v=dhcQG_KItZM

When he knows enough words and sentences, then the grammar would fall into place when he practices it enough