Devils never announce departures until they've signed for other teams and then there is usually a statement.
(There may be some crossed wires here, re-reading comments)
Apart from Louis who was announced as leaving without another side announcing him. I do note that usually they wait until the other team announce though, so fair point.
HOWEVER, as for other points - its not disrespectful to announce a player departing before he signs for someone else - as has happened a load of times by other sides before players sign with us - as long as you don't steal the new team's thunder by naming the new team.
I.e. Devils Announce Departure of NM Tarun Kozun - Devils thank him for his service and wish him well in his next venture (without naming Blaze or EIHL).
But whilst I think thats the point made above by others - its other people's opinion, not mine (LOL). I don't mind Devils fans finding our from the new team personally. I don't see the issue.