It is a common feature of Christianity, journeying.
We go on pilgrimage together, walking alongside one another, helping each other as we go. This Christian way has been with us since forever!
The Emmaus road story is about a journey, and fellowship together.
What am I getting at?
When someone leads worship at which another is preaching, is it not normally the case that these two people should sit together, before the congregation, pray together before and after the service and generally help each other along the way?
For me this is primary, for others evidently not. Flattered though I was to be left to take the service without guidance or help, although frankly by now this should be second nature… There was a sense of distance between the sermon, (not mine) and the rest of the service, even though I had tried to integrate the two.
Journeying between colleagues or those put together to prepare worship should be just that, not separate paths with no relation between the two.
At an even more basic level, the lack of support shown by not participating was a distinct lack of professionalism and grace towards another member of the Christian family!!