That's a correct guess. In 25 years of experience in scanning my negatives, I've never been able to 'rescue' via scanning and/or post-processing a very thin negative. A poor negative always, without exception, yields a poor scan.
I'll go even further: after a bit of experience, it even becomes possible to identify from the scan, whether the negative was too thin or not. The negative is the final word, of course, but the scan often offers important hints. If you do this for years you can pick up, from a scan, whether photo-shopped or not, whether intensely 'curved' or not, if the negative wasn't ideal for scanning.
I've never, without fail, seen a perfect scan from a very thin (or very thick) negative, even if the person producing it was a Photoshop wizard. In fact, Photoshop wizardry doesn't exist - it's an excuse wet printers often use to justify their poor understanding of the hybrid process. You can't polish a turd. Of course, everything is now changing with AI-produced or doctored images.
But to go back to your question above, in my own experience, and my own workflow, the best scans are obtained for a negative exposed and developed for a target gamma in the interval .55-.6. This is basically a target gamma in the region of what was considered 'standard' in the days of wet printing with a condenser enlarger head.
Sounds honestly not so surprising to me, as the engineers who designed film scanners had to start somewhere and my unsupported assumption is that they would have started designing the device to perform well in a reasonable distribution of densities centred at gammas of negatives exposed and developed according the accepted standard at the time.