ἱεράτευμα in 1Pet. 2:9 a collective noun?

1Pet. 2:9 like Exodus 19:6 LXX reads βασίλειον ἱεράτευμα an adjective with a collective noun. Well thats what J.H. Elliott (1 Peter, Anchor Bible) wants us to believe. He claims that the referent of ἱεράτευμα cannot be individual believers because nouns ending in -ευμα are collectives. That is just one piece of his argument, one scrap of evidence.

Well, when I read something like this, claiming that a noun or adjective suffix has some sort of lexical semantic significance, I am always skeptical. So I searched Liddell & Scott Intermediate for all lexical head words ending with -ευμα. There were about 95 of them. Then I read the definitions for all 95 words and set aside words which would not tolerate a collective sense. I think there were 19 or 20 words. About 75 words would at least have a possibility of being used with a collective sense. They didn’t necessarily require a collective sense but it seemed that they would lend themselves in a suitable context to being understood as a collective or a mass noun. This isn’t science. Very subjective. But at least it suggested that perhaps there is some sort of connection between the suffix and the meaning.