Though it had been thought for quite some time that there was a rule preventing the Vegas Golden Knights from trading any player selected in the expansion draft back to his original team until January 1st of 2018, Pierre LeBrun of TSN clarifies the rule. There is no rule to block those trades, and teams are free to reacquire the players lost in the draft should they come to an agreement with Vegas.
Instead, the rule in place which was misunderstood is one blocking teams from reacquiring players they traded to other teams just before the draft. That would have stopped teams from just moving pieces around to block Vegas from selecting them, only to move everyone back after the draft. The new understanding though adds some wrinkles to the next few months, as teams like Nashville or Ottawa could potentially bring back players like James Neal or Marc Methot.
While there likely won’t be many instances of players being sent back, it could come into play for some teams who can’t seem to fill the new hole in free agency. For teams like Washington, who lost Nate Schmidt and may have trouble finding a suitable replacement after also losing both Kevin Shattenkirk and Karl Alzner to free agency, having at least the option of bringing him back is helpful. This is just another way in which the league can help Vegas, by opening up another team for them to negotiate with as they try to flip their selections.