I don't think reinforcing foundations can ever be the wrong answer, and like I said, since it was a dog walk injury, I'd especially be focusing on that.
However, I agree that the only way to learn to handle sequences and a course is...well, to handle sequences and a course. You do all your ground work of course, but when it comes down to it, it is a new skill all together.
I wish there was a good, clear answer. It is clear how much you care for your dogs and their well-being, both mental and physical. But, as I'm sure you know, at the end of the day - you are going to have to decide whether or not to gamble. I hope the specialist will be able to offer some good information that will make the decision more obvious for you.
For what it is worth, as I was thinking about this last night, I realized I know another agility dog who recently recovered from the same injury (I assume - the owner called it a groin pull). I know she did a ton of rehab with him, and he's been back running agility and kicking butt most of this season. And he's a definite high-drive dog. I know all dogs are individuals, but this dog clearly recovered so well, I figured it was worth mentioning.