If the subs being nuclear was the problem I'm sure french would have arranged for that. I can't find a source for this but the submarines in question are essentially refitted from being nuclear to diesel-electro for the export to other nations.

I think the political view in Australia has changed from "we don't have nuclear infrastructure" to "we can build up nuclear infrastructure while the US builds the subs"? This is just my assumption.

If I'm wrong on any of this please correct me.