Hejduk was absolutely soft. Sure he could withstand abuse in front of the net and on the cycle, but he never initiated contact and downright avoided it when possible. A player like Hejduk, who was so smart positionally and had such a good in tight shot and set of hands, did not need to be a physical player. I don't criticize him for this. But seriously, I can't think of any hit laid by Hejduk in his entire career. I still love him, though; my favorite player too.
I think you and I have a very, very different idea of what "soft" means. Just because a guy doesn't lay big hits doesn't mean he's soft. If Hejduk's soft, then over half the league is soft. Mikko Rantanen doesn't often initiate contact, he uses his size and strength to secure pucks and create space for himself, but he sure as hell ain't soft. Hejduk was just a smart player with very good positional sense, as you pointed out. He knew there were things he was good at and things he wasn't.
Joe Sakic never really laid any big hits, you really gonna tell me he was soft? He just relied more on speed than power in his game. Forsberg was the exact opposite.