Maybe because he is a good heart, and can take the "worry" of writing and delivering a name.
I'm talking about the whole idea of putting notes into the kotel. Why put in a note if Hashem can listen to our tefillos everywhere?
C'mon, it was a supporting wall built by King Herod (who according to the gemara killed out almost all of the chachamim) in order to enlarge Har Habayis. And why did he want to enlarge Har HaBayis? B/c he wanted to build himself a large beautiful building on part of it, and to do that, he had to flatten out the whole area.
And to the best of my knowledge, our older sources don't discuss davening there. It started at a later time in history. The Rambam discusses davening on Har Habayis which is the true makom kadosh.
At the minimum, give the note to s/o going up onto Har Habayis and ask them to put the note down there somewhere.