The question is, as you say, does a particular Lutheran meet the criteria? Simply reiterating the criteria does not answer this in any way.
in danger of death or some other grave necessity
Grave neccesity as defined by the bishop. It does not have to be a dire circumstance, but can refer to being isolated in mission territory and similar circumstances, according to Vatican guidance. Other bishops’ conferences have understood it as applying to married couples.
does not have access to a Lutheran minister
No Lutheran minister would be celebrating the Jubilee declared by the Catholic bishop, so none would be available. The particular thing being celebrated, the commitment to one another in Christ, can only be celebrated by the couple together.
makes the request of their own volition
I do not know how couples were chosen for invitation, but I can see their marital commitment as an implicit request to be more closely in communion with Christ, especially if they have accepted an invitation to attend, as a married couple, a Jubilee mass at the cathedral.
confesses Catholic faith in the eucharist and is properly disposed
Again, this may be implicit in the way they were invited. I do not know. I know some dioceses assume Anglicans and Lutherans have the same faith in the Eucharist that we have.
Some of these seem like a stretch to me, but I am not a bishop and am not familiar wih the way marriage is understood and celebrated there. I don’t even know what the rejected document from the German bishops said. It just seems like these criteria, far from making intercommunion impossible, may not even make it rare.