Hah! I think that I wrote that claim myself. The reasoning behind it is that TUDCA and PPC are both emulsifiers which can help solubilize lipophilic ingredients in the GI tract. Both TUDCA and PPC can form micelles which facilitate lymphatic absorption. Thus TUDCA/PPC can increase the absorption of lipophilic ingredients, such as steroidal androgens, when they are taken together orally. I'd imagine that the effect would be fairly modest, but it's certainly better to take them together as opposed to taking them apart.
...And for what it's worth, other bile acids such as sodium taurocholate are widely used as excipients to improve the oral bioavailability of lipophilic drugs. There's one study at PMID:9510986, and many dozens more like it.
As for milk thistle: There's a study which states that it decreases AR function in prostate cancer cells. I don't know if we can infer from this that it decreases AR function in a general sense. Even if so, the concentrations which were needed to decrease AR function in prostate cancer cells to a significant degree were very high. Such concentrations seem to be frankly unattainable with any reasonable dose of milk thistle supplements. (It took a concentration of 75uM silybinin, and the bioavailability of polyphenolic flavonoids from milk thistle is exceedingly low... but as the 'active site' for these milk thistle phytochemicals is the liver itself, systemic bioavailability is probably a fairly minor consideration.)
I can't post links. For more information, Google: "Silymarin inhibits function of the androgen receptor by reducing nuclear localization of the receptor in the human prostate cancer cell line LNCaP", and "In-vivo Kinetics of Silymarin (Milk Thistle) on Healthy Male Volunteers"