If you believe Russia Wiki - good luck! No, they did not return. He told about it for Radio Svoboda. Yes, Mr. Navalny page is good for some information but it may not be sufficient for everyone.
Everyone can challenge usage of Prominent. He was prominent since his work and opinions are source for many Western experts in Russia. He was considered an expert on the Kremlin regime. He was often correct in his predictions regarding nominations in Kremlin. I do not see any reason to challenge accuracy of the description of his figure on Russian political scene as a prominent.
Thank you for critical reading of the article. I am still convinced it provides the best information you can find in English.