I assume by fleeced he's not talking about Simmons, but the other guys. But Drummond was still a back-up who wasn't coming back, Curry probably would have been included in an off-season trade if this hadn't happened, and this team wasn't going anywhere without a move. And the picks are worth less than Maxey or Thybulle (and keeping Maxey is looking especially good right now - small sample, but he, not Harris, may end up being the third star).
In a perfect world it would have been a one-for-one trade with Simmons' potential weighed against the older Harden's Hall of Fame resume but the the Simmons situation was what it was. Both teams could have sucked it up the rest of this season, and neither of them would have won anything. The Sixers has more to lose given Embiid's age, performance and (so far) health. The Nets already had the Kyrie situation and an injured Durant and could have written the year off if they had to.
None of it means anything until we see what they do in the second round or conference finals, but they've got a legit shot at the top seed now, and have almost certainly gone from a possible 4-5 to a 2-3.