Salam
Lets not get ahead of ourselves.
shaykh Juhany is in Makkah so he led. He nornally lives in Madinah but I think he must have been in the area and was called up by one of the others (shaykh Talib, shaykh Shuraim). Because he has led in the Haram before, he can go forward. Same for shaykh Mahir. Not any Joe can go and lead in the Haram. But it's nice to see a young face leading. I remember him from uni. Used to come every now and then. When we were there he was sort of senior TA style. Used to come and do some of the classes if the other shuyukh were busy.
I dont know if its a full-time post, might have to call him and find out.
Wassalam