It may be likely that the speech giver themself would have the speech written down or recorded. The best reference would be a document or reference to a document that indicates they either had in their possession or had read the written speech. I do not believe that exists either, but am not familiar with the bibliography of the referenced book. One thing seems certain, Ellis wrote serious non-fiction later in his life and this was a product of it.
So, in the end, this particular speech, and perhaps many more, become a matter of specualtion and belief. The arguement should be couched in those terms rather than the unforgiving, absolute terms that some seem to want to couch it in IMHO.
I for one believe that is would be like Crockett to do this and believe he could have said it. Did he actually say it? Can;t say and don;t know.
Regards.