That is hypothetically true.
At any rate, the point of my earlier remark was an attempt to prevent an argument that was based on a failure to notice mixed-definitions of "mathematically excluded."
-- But the fact is he is not eliminated from getting 1,237 delegates until someone else does. --
Under the conventional definition, it is possible for all candidates to become "mathematically excluded," unless a race has only two candidates from the get-go.
The conventional definition looks at the number of delegates a candidate has, and adds to that the number of delegates yet to be selected. If that total is less than 1237, then the candidate cannot get to 1237.
I think the disagreement on mathematically eliminated actually comes from one saying “during the primaries” and the other saying “at the convention”. If both Trump and Cruz get their delegates to vote to keep rule 40, then it will be one of the two of them, and most likely it will be whichever can garner support from the delegates at the convention. If past history of close, or contested conventions is any indication, they will both be on the ticket.