Tasktroubleshooting and machinery task

I don’t work with the machinery task often but I have a current client who is using it.
We noted that it does not include <tasktroubleshooting>.
It of course allows for <steptroubleshooting> since that’s part of <step>.
Was this an oversight or was there a reason not to have it?
Is this whole question irrelevant because we won’t be supporting machinery task moving forward?
My understanding is that machinery task (and the L&T domain) DTDs will be updated for 2.0 conformance.
So does that mean machinery task will have a 2.0 DTD that allows nested steps?
And if we are doing that can we add <tasktroubleshooting>?
Or will all this need to be handled as a specialization?
Dawn