Somewhere on one of the IEEE pages you will read that Wallace Thornhill has a BSc from the University of Melbourne (in Australia, not Florida), in physics and electronics.

In the PDF document you will see a reference to Hannes Alfvén. A few minutes searching ADS, starting with "Alfven, H" in the author field, will turn up lots and lots of published papers. Almost all of them are filled with equations, numbers, and quantitative stuff; they also provide references to other material, where Alfvén has stood on the shoulders of others' work.

From that IEEE reference, and some searching on EU pages, you can estimate that Wallace Thornhill graduated in 1970 (+10 -15 years).

What were physics students taught, at the University of Melbourne, a few decades ago? Could they reasonably have been given passing grades, by their physics lecturers, for models developed and presented without references or equations? I can't be sure¹, but I think it quite likely (>80%) that any of Thornhill's physics lecturers would have given him a failing grade for something like the (alleged) ICOPS poster with his name as an author.

How hard would it be to turn the ECM, as presented in that PDF document, into at least a first draft quantitative model? Read a few of Alfvén's papers, take a plasma physics graduate level course, and I think you'd agree that 1 hour to 1 day would be a good (95% CL) first estimate. Of course, Thornhill is no Alfvén, so let's be generous and say it'd likely take him 1 week to 1 month to come up with such a first draft ... OK, maybe a year.
That's from the webpage of the link on page 10 of PDF document ("Advanced Predictions of "Deep Impact"") (my emphasis).

So why, after 30 years' of work, does a person with a BSc in physics put his name to a document so devoid of anything quantitative? A document that's purportedly a poster at an international plasma physics conference? Concerning a model that is supposedly based on (plasma physics) ideas developed by Alfvén?

Here's my entirely speculative guess as to the answer: because any quantitative model, even an OOM (order of magnitude) one, would be obviously inconsistent with a large number of good, independent, observations and experimental results ... and thus consigned to the dustbin of science history.

Of course, if you don't have at least a BSc with a major in physics², you are likely to read the above and simply wonder ... where does Nereid's confidence re those assertions come from? Hard to address adequately within the limits of posts in BAUT, but open your mind to this: if comets are "asteroids on eccentric orbits", why are some objects with orbital eccentricities in the same range comets and others asteroids? Or this: if comets (or asteroids) are charged bodies on orbits within a constant, radial electric field (centred on the Sun), why can't those orbits be predicted by force laws based on electromagnetism?

¹ inputs to flesh this out greatly welcome!

² or something similar.