Without knowing the full story it is hard to say if this is a good idea or a bad one. The purpose of statins is to reduce risk of cardiovascular disease either in the first place or after an event like heart attack or stroke has occurred. If the original assessment of absolute cardiovascular risk over 10 years was high, and statins were started for that reason, then unless that assessment is recalculated, then staying on them is the correct approach regardless of lipid levels. If they are being used for secondary protection then stopping them is always the wrong move.
If the loss of weight and improved blood pressure, lipids etc were enough to reduce risk to below 10% over the next 10 years then stopping might be correct, but it is definitely not as simple as better lipid numbers after weight loss. Looking at statin use based on absolute cardiovascular risk is the correct way to view it but it is not super simple or obvious. Anyone who has or had severe obesity is likely to have high absolute cardiovascular risk, and there is a fairly high chance of that still being the case if weight is lost especially if older. And there is a reasonable chance that damage has already occurred that will not be known about unless it is looked for.
I ended up diagnosed with early heart failure and coronary artery disease after losing a lot of weight and without symptoms, where treatment with statins and other medications reduce 10 year risk from about 25% to about 12%, but if it had not been looked into I would not have known until a heart attack years later, which might still happen , but being half as likely sounds good to me.
