There has been debate on this topic for as long as I can remember. There are arguments on why you should and why you shouldn’t strength train, but even though scientists and top coaches have spent time on this topic for years, there is still no agreement on the most optimal winter training for a road cyclist.
The keywords in this discussion are ‘lack of evidence’ because of small study groups in the scientific projects. For example, when the medical industry develops new medicine to prevent heart attacks, they can conduct large randomized trials to show even small, but still significant, differences between different medications. They include thousands of persons in the study and follow them through several years. Thus, the statistical power is much, much higher.
Unfortunately, that is not possible with trained cyclists, and that is why we will never see any randomized trials that conclude whether strength training makes us better cyclists or not.
Btw. Are you visiting the gym this winter?