Coach sits... or not

[varefump]

Federation Rules - Between sets 1 and 2, the R1 observes the libero and one of her teammates pulling off their uniform tops to switch from being libero to team member and vice versa. The R1 gives a yellow card to both players. Since the players were standing in the bench area when they pulled off their uniform top, does this mean that team’s coach can no longer stand for the rest of the match? In other words, would the coach also get carded? The bottom line is... are the players considered BENCH PERSONNEL between sets?