Again, you are talking about controlling the decision making and play time of the player and how they play their adventure. Honestly, what your asking for is a terrible idea
No, it's definitely NOT.
But setting the limit to "two long rests" may be pushing things too far.
We already argued that timed restrictions should suggest a pressure while being forgiving enough to leave to the player room to do side activities as long as he doesn't deliberately waste tons of times.
Asking to solve all the druids problems inside TWO long rests is basically punishing anyone but people going for an optimal path.
Even as someone who uses the rest as little as possible I'd be against it.
But I definitely wouldn't be against setting that limit to, say, ten full days. Once again, the ticking clock doesn't need to be there to actively punish a player, it just needs to set a limit to how indecent he can be with wasting time ignoring any remote sense of urgency.
I'd be fairly confident basically anyone could make to the goblin camp and back with Halsin inside a limit of 10 long rests, no matter how utterly incompetent with resource management... But at at least that would prevent a downright exploitative behavior like "Yeah, fuck it, I'm going to do a long rest every two goblin killed and blow my entire load of spells every single time".