I don't think your premise is correct. We'll have to see. Trump was not the overseer of the special counsel. Rosenstein was Mueller's boss. Trump had no line authority over it; that is why he tried to get other folks to fire Mueller. Rosenstein initiated the special counselor investigation because Trump fired Comey.
The FBI investigation started long before the special counselor and the FISA warrant. The FISA warrant only opened up more investigation of Carter Page. Repubs claim that the FBI were spying on Trump. The CP warrant happened in Oct 2016. The FBI investigation on Russian interference began in July. Rosenstein made the SC appointment because of the WH memo regarding the firing of Comey and Comey's statement that Trump has asked him to end the investigation. Because of the appearance of Trump's obstructionist behavior, Rosenstein, put Mueller over the existing FBI investigation.
Here is a time line:
- 2013 Russian intelligence tries to recruit Carter Page
- 2014 Carter Page subject to an FBI FISC warrant for his connections to Russia
- March 21, 2016: Carter page announced as Trump's foreign policy adviser. Carter Page is on the FBI radar
- March 21, 2016 Papadopolous joins the Trump campaign
- March 24, 2016 Papadopolous meets with Putin connected Russians in London
- March 31, 2016 Papadopolous meets with Trump and Sessions et al and says he can facilitate foreign policy meeting between Trump and Putin
- April 26, 2016 Papadopolous meet with his Russian contacts in London again and was told by them that Russia had Hillary's emails.
- ~May 10, 2016 Papadopolous tells an Australian diplomat that Russia has Hillary's emails.
- May 26, 2016 Papadopolous tells the Greek foreign Minister that Russia has Hillary's emails
- June 9, 2016 Trump Tower meeting with Russians and Trump family etc.
- June and July 2016 DNC emails leaked by DCLeaks and WikiLeaks
- Australia reports conversation with Papadopolous as soon as the DNC emails go public. Papadopolous is on the FBI radar
- July 5, 2016 Steele shows 2-4 pages of the dossier to an FBI agent in Europe. The first few pages of the Steele dossier are shown to the FBI
- July 31, 2016: FBI begins investigations of Russian interference in our election.
- late August - Sept 2016 FBI counter intelligence takes over the case and requests any more information that Steele has
- late summer Steele meets with a small group of national security reporters, but no stories are run. Word of the dossiers existence begins to leak out.
- late September 2016 Steele meets with FBI in Rome and shares what he has up to that point. The FBI tells Steele that the FBI is already looking into a campaign aid called Papadopolous
- Sept 2016 FBI begins a second investigation into Carter Page
- Oct 2016 Steele breaks off talks with FBI because he thinks they ignoring his information and focusing on Hillary's emails.
- Oct 2016 Steele had compiled 33 pages (16 memos), on Oct 31 Steele gives those pages to Mother Jones.
- Oct 2016: FISA Warrant issued for Carter Page
- Oct 31, 2016 DNC learns that they paid for the Steele dossier (from Mother Jones publication)
- Steele continued to work on the dossier into Dec.
- Early December 2016 Final 16 memos were delivered to John McCain
- Dec 9, 2016 McCain delivers all 16 memos to James Comey
- Steele finished his work on Dec 13, 2016 when he wrote the two page December memo.
- Early January 2017: Obama was informed of the dossier and what it contained and about Russian interference in the election
- January 6, 2017 Clapper and Comey told Trump about the Russian interference in the election. Clapper left the meeting and Comey told Trump about the dossier and what it contained.
- By the end of Jan 2017 the FBI, CIA, NSA and DNI were all investigating Carter Page.
As you can see, the FBI had ample evidence to reopen an investigation into Carter Page and look into Russian interference: Papadopolous, Carter Page's past and the initial pages of the Steele dossier. All this was months before the FISA warrant. The evidence just got worse as time went on.
You should read your link more closely. The part of the dossier in question is only the part where Steele talks about Aleksej Gubarev and used bad info. Buzzfeed redacted his name from the published dossier. There is no mention of him in the first 30 pages of the dossier. The redacted parts [about him?] consist of 3 lines on page 31 (from Oct 18) and two more lines on page 34 from December. Steele accused Gubarev of hacking into DNC computers.
Five lines of redacted text out of 35 pages does not a fabrication make.
More trash trolling. Get you facts straight. Originally, the FBI had agreed to pay him to keep working, but they never did since there was a falling out. He was never paid by the FBI.