WHen it has happened to me, there was NO evidence of the clutch going in or out of engagement.
ANd since the car perfectly happily engine brakes,I don't think it will disengage the clutch based on throttle position while in motion (other than at VERY slow speeds).
'95 Alpine M3 LTW
'00 Dakar M Roadster
'02 Topaz M3
Red/White SRF #4 (Chassis 561)