it says not more than, which seems reasonable as a maximum sentence if you consider AI development a similar existential risk to something like Nuclear weapons research
i would assume the average sentence would be less than half, even 1/10th of that, and the maximum is set that high for extreme offenders (bernie wants to imprison sam altman soo bad)
you can have dario and altman's head for all I care, but realistically you're going to suspend the constitution to get it and transform the US into a totalitarian regime.