Did anyone of you who runs a Lightning routing node experience someone connecting privately to you, route coins through you, then close the channel?
It didn't happen to me so I guess that only extremely large/well-connected nodes experience it.
I believe Lightning deniers foresee something that they don’t want every Bitcoin user to discover.
I am not sure why you mentioned Lightning deniers here. The above sounds to me like a use of someone's Lightning node to mix coins.