He <spoke of> the restless poor being a threat to political stability

[park sang joon]

But he complained that those who had borne arms for their country enjoyed nothing more than air and light and that they had fought and died to maintain the luxury and wealth of others. He spoke of the restless poor being a threat to political stability and complained that the small farmer, who had been the backbone of the republic, was disappearing
<Violence against the Gracchi Brothers http://www.fsmitha.com/h1/rome11.htm>

I think the underlined clause should be the structure "speak of A as B," and so that "as" should be positioned before "a threat."
I'd like to know my thought is right.
Thank you in advance for your help.

 

[Enquiring Mind]

Hi psj. The "as" is optional in this construction (using an ~ing form of a verb) in this context.

He spoke of the restless poor being a threat to political stability, and he spoke of the restless poor as being a threat to political stability both mean "he said the restless poor were a threat ..."

He spoke of park sang joon as having a very good command of English and he spoke of park sang joon having a very good command of English both mean "he said psj had a very good command ...."

If you're using a noun in the comparison, not using an ~ing form of a verb, then you need to use the "as".
He spoke of his father as the person he admired (the) most. (He said his father was ...)
He spoke of his wife as the best thing that ever happened to him. (He said his wife was ...)
He spoke of Shangri-La as the place he would most like to visit. (He said S-L was ...)

 

[park sang joon]

Thank you, Enquiring Mind, for your very helpful answer.