Do you have a reference for any of this?
What you seem to be saying is that anyone on more than a minimal (500 mg) dose of Metformin has no need of statins. Many here seem to be on 2 or more tablets a day (by my maths 2 * 500 mg = 1 gram) so in theory they should be seeing a drop in cholesterol as if they were on statins.
I find
http://www.medscape.com/viewarticle/849463 which seems to have had only 90 T2Ds on Metformin in the study, and seems to be an analysis of existing patients not a trial with controls.
It also says: "Compared with the other participants, those with type 2 diabetes who were receiving metformin had much lower concentrations of the six metabolites — independent of multiple variables (sex, body mass index, physical activity, alcohol intake, smoking, systolic blood pressure, HDL cholesterol, triglycerides, HbA1c, fasting glucose, and use of statins, beta-blockers, ACE inhibitors, and angiotensin-receptor blockers)."
So the 90 T2Ds could also have been on a varied cocktail of other drugs.
The conclusion seems to be that "something is happening but we are not certain what or why".
Most other hits using Google seem to be referring back to this study.
Interesting:
http://www.diabetes.org/newsroom/press-releases/2017/petrie-scientific-sessions-2017.html
However, please note (my highlighting):
"REMOVAL studied 428 middle-aged adults with longstanding type 1 diabetes--on average for 33 years. The patients had
three or more risk factors for cardiovascular disease, including BMI over 27; A1C greater than 8.0; known CVD/peripheral vascular disease; current smoker; high blood pressure; high cholesterol or triglycerides; strong family history of CVD; or duration of diabetes more than 20 years."
So at first trawl I haven't found anything that seems to say that 1 gram or more per day of Metformin is a potential alternative to statins.
Oh, and statins took my cholesterol way down but the side effects were unacceptable. The 1.5 grams per day of Metformin does not seem to be having any similar effects on my lipid profile.