I apologise for the length of the following, and I do think it’s justified, if only against the idea that ‘Proper Noun Capitalization for Type of Thing’ could ever work.
In the example, doesn’t ‘Dedicated’ derive its capital solely from differentiating various ‘participants’? How could the description be more worthy of capitalisation than the subject it described?
Isn’t the real Question, how or why you understand ‘that’ as a proper noun when Participants must be more than equally worthy of capitalisation?
Might that explain how the rule coming up many times in reports you need to write is confusing? (I suggest you try explaining the rule as you might to a learner, then look at what confusion remains…)
When my English teacher asked for examples of proper nouns I suggested ‘Red Kangaroo’ as opposed to any other, nondescript kangaroo, and was rightly corrected. A ‘red kangaroo’ is no more ‘proper’ than any other.
‘Skippy the Bush Kangaroo’ earns his initial capital twice; first from starting the sentence, which is not relevant here. More solidly, ‘Skippy’ is a personal name; a proper noun, deserving a capital wherever it falls in the sentence.
’… the Bush Kangaroo’ could never ‘earn’ capitals in ordinary English. Rather, those capitals are given gratuitously, under the aegis of a TV title.
On the simple basis of what is or is not a proper noun, I think this would be better served in English Language Learners.
Here, exceptions to the normal rules most obviously include headlines in print; titles of books, films and TV programmes like ’Skippy…’ or the like and, yes, product descriptions.
Product descriptions clearly cover Emirates’ use of capitals for Business Class, along with 187 examples to be found anywhere we look.
Consider the every-day English use of ‘… the man who would be king…’ which would earn the one capital, ’T’, only if it began the sentence.
Contrast that with Rudyard Kipling’s novel, and John Huston’s film thereof, both capitalising every word in that same ’The Man Who Would Be King.’
Headlines play at least equally, if not more fast and loose with normal rules, most readers allowing them licence to gloss over argument about the need for brevity or impact.
Beyond headlines, titles and product descriptions, house style over-rides all else… and on house style no-one here can advise, unless you’re struggling to devise a house style, which would be worthy of its own Post, somewhere such as Writing SE.
(Not that it matters in terms of noun capitalisation and there are not nor ever could be ‘more nearly unique…’ anything. The difference between ‘unique’ and ‘unusual’ is very simple. ‘Unique’ is by its nature incapable of qualification. What is ‘more nearly…’ anything could be as unusual as you like but it could never approach uniqueness.)
If ‘dedicated’ and ‘auxiliary’ being the types of participants changed anything, as when ‘… dedicated participants have a list of requirements to enter (anything)…’ why did you back away from using capitals there?
As Barmar points out, if this is for ‘a gov doc with rules and legal aspects’, the lawyer - or anyone else - drafting it should be familiar with the conventions.
Can you say exactly what is meant by ‘this is for a gov doc’ and what ‘rules and legal aspects’ apply?