I think Brink caught them by surprise, going into camp, and even the first week of camp, he was ticketed to LHV for "seasoning," coming off a subpar season due to hip surgery. Then he plays himself into a longer audition, into a cameo to start the season, and then into the top 9 as the best playmaker on the team.
At the same time, Couts and Atkinson and Farabee have exceeded expectations. So suddenly they have (10) top 9 forwards for 9 slots, 1 true LW, 4 centers, and 5 RWs. Now Laughton can move to LW, but you still have to shift one RW and bench another.
Right now they're playing Tippett and TK on the left side, Tippett is struggling a bit.
If you move Laughton to the 4th line you have to leave both on the left side (or move Foerster or Atkinson or Brink over). And you reduce Laughton's trade value.
I think this will be resolved in the next few weeks, if the AHL forwards keep playing well, Briere will be more confident that he has the depth to handle injuries, so he'll be more wiling to trade a forward. And teams are already losing forwards around the league and lack the cap room to easily replace them - what team has both an extra forward and the cap room to facilitate a trade?