Make the call only if the Linesman, who is responsible for the blue line is out of position and UNABLE to make the call. The Linesman who is on the other side of the ice shouldn't make a habit of doing it.
In how you describe it, the Linesman, who's line it was, was able to make the call and he waved it off.
You also state that the player's body was not completely across the line. The player's skates determine whether it's an offside or not. If both of his skates were not completely over the line, while he was sliding into the zone, he was not offside. If one skate is in the zone and the other skate is in contact with the ice and not completely over the line, when the puck is carried across the line, he is not offside. If one skate is in the zone and the other skate not completely over the line, but not in contact with the ice, when the puck is carried across the line, then he is offside.