Well I was at a discussion last night hosted by Muslim refugees at the Nurture Society, but I didn’t think to bring up this topic. We had an interesting discussion about religion as a force for good and bringing people together. And they gave us a Turkish meal, which was excellent. These Muslims are mainly Gulenists, from what I gather, so they are fairly liberal in outlook and in particular are very pro education.
I don’t know where the Christadelphian I was talking to got the idea of 120 years in connection with Muslims. Muslims are a very diverse community, of course, it’s possible some segment of Islam ascribes some importance to the number 120. The connection to a generation seems more tenuous. The only thing I can find online is reference to a word qarn which can mean an age or 120 years.
https://www.jstor.org/stable/10.1086/669204?seq=1#page_scan_tab_contents