The guy was probably privately reproved and on restrictions.
I had first hand experience in my younger days :). Such fond memories growing up in ' the truth '. A teenager facing 3 elders spending a solid 20 mins humiliating me in front of my family in order to reprove me.
Being privately reproved usually means you were a whisker away from being disfellowshipped and as such, you would lose any privileges you had as a baptised brother, including giving prayers.
When I asked what to say if someone should inadvertantly ask me to pray, the answer was I was required to politely decline.