Until late in his career he kept writing on “old economists” like Cassel, Böhm-Bawerk, and Ricardo, for example (for instance, see his co-authored article on Ricardo published in HOPE in 2006) .
However, it is indeed quite curious to see this same man making the following comment about a candidate that he was suggesting to his friend, Lionel McKenzie, to be hired at Rochester. After pointing out that the person was considered to be one of the best teachers at Harvard, who taught a course on development economics but had a temporary position there, Samuelson wrote:
Also, to be meticulously honest, I did hear one criticism of his course on economic development, that he spent a large amount of time on Ricardo’s and other ancient writers’ theories rather than on exciting current topics
Worth noting that Samuelson did not say that the person spent much time reading Ricardo and ancient writers in the original, but rather spent time with their theories. Nothing against someone willing to see courses covering the frontier of knowledge, but I found interesting to see Samuelson writing this at the same time he himself spent a good part of his career connecting his theoretical developments to those of ancient great economists.