I'm not sure this follows....
Electoral design and voter welfare from the US Senate: Evidence from a
dynamic selection model
Gautam Gowrisankaran, Matthew Mitchell & Andrea Moro
Review of Economic Dynamics, January 2008, Pages 1-17
Since 1914, the US Senate has been elected and incumbent senators allowed to
run for reelection without limit. This differs from several other elected
offices in the US, which impose term limits on incumbents. Term limits may
harm the electorate if tenure is beneficial or if they force high quality
candidates to retire but may also benefit the electorate if they cause
higher quality candidates to run. We investigate how changes in electoral
design affect voter utility by specifying and structurally estimating a
dynamic model of voter decisions. We find that tenure effects for the US
Senate are negative or small and that incumbents face weaker challengers
than candidates running for open seats. Because of this, term limits can
significantly increase voter welfare.
The welfare effects of term limits are more complex than this, for starters. But I'm not sure that this argument is right even on its own terms.