I find the linked article you posted, VERY misleading. I tried going through the sources/references listed at the end of the article and the only one I could find that mentioned an antiestrogenic effect of SP was referring specifically to prostatic tissue.
The article itself also says that SP is likely ineffective in treating BPH but if you dig into the research, it turns out there is NO standard way of producing/extracting SP into capsules so comparing one brand to another or even production lots within a single brand is impossible. There is too much variance in the amount/strength of the likely active component of SP (lipidic liposterols). There is a company in the EU that prepares a standardized preparation lipidic liposterols derived from SP and the evidence shows it has significant effect on BPH symptoms (Permixon, Pierre Fabre Médicament, Castres, France).
Doing a search on "antiestrogenic effects of saw palmetto" on scholar.google.com yields similar results. The anti-estrogenic activity has been noted in prostatic tissue, not "in the body" as stated in several places in the article. To further complicate things, SP apparently has both anti-androgenic AND anti-estrogenic effects experimentally.
My personal experience is that PM worked just fine without the use of SP. I can't say that SP had NO effect or that it opposed PM, just that PM alone, worked fine.