I found one reference that says this, "According to has been called a prepositional phrase, but strictly speaking, according is a participle in the sense of agreeing, acceding, and to alone is the preposition."
But, in this case, I think what we are dealing with is literary license used extensively by journalists.
This quote is from a journalistic piece, right? In journalism, they often use this construction to tell the 'source' of quoted (or paraphrased) material. These same journalists then cause us further confusion by adding in additonal facts after the 'source'.
The journalist spoke with 'a day camp director'.
This conversation took place on a Thursday.
The day camp director said, "Members and officials of a private swimming pool in a Philadelphia suburb reacted to a visiting group of minority children by asking them not to return and pulling their kids out of the water." (Actually, this was probably NOT a quote from the day camp director, but summarizes or paraphrases what this person told the journalist.)
The day camp director also said, during the Thursday conversation, that the parents are considering legal action.
In this particular usage - where the 'according to' is to introduce the identity of the source of the information - I have NEVER seen this without the comma - even if that part comes first.
No, I do not believe that the comma has any significance as to the relative importance of the legal action. It's merely to separate the information from the source-that-provided-it.According to a source in the ministry, the water level will continue to rise.
The water level will continue to rise, according to a source in the ministry.
The quote is a poor example of written English. I would certainly not write a sentence like this for a college essay. It has a place in journalism, but not in academia.