In other words, there is no policy re. frequency of posts, as long as the posts are not spam. Correct?
There is none. There are people making a lot of posts (20+) a day. However, what you are doing is 'bumping' the thread by posting 'updates'. Rule 13 applies to that.
If you are going to argue that the marketplace rules (or at least no more then one update per 24 hours) rule is going to apply in all sections (which I don't think is an appropriate conclusion) then I might question why this rule is not being enforced across other threads in a similar manor.
The "Bullish News and Articles" thread was updated at 10:48 PM on Oct 7, 2015
here, and was later updated a second time at 11:29 PM the same day, roughly 45 minutes later
here.
AFAICT, both threads are roughly the same with one discussing bullish stories and the other discussing bearish stories.