I think that the gun obtained by the event of the 4Th July, should be tradable, giftable, or put in the Marketplace, because in the end this shouldn't lead to any result because all the players will still be able to choose whether to give the gun or less.
Apart from that, the fact that those who didn't participate to the event, for little desire to take the chests, or for important reasons that couldn't avoid, can't in any way to have that gun to me seems a little unfair.
(Maybe the fact that I didn't participate to the event for good cause, might have changed the content of this text, however, is what I think °-°)