Ah - this from Don's link is probably helpful in understanding Wallace's perspective. If this is true that he was an Idealist, Wallace can't have ultimately been very interested in interpreting Epicurus sympathetically:
QuoteWallace had wide intellectual sympathies and found matter of agreement with philosophers of different schools; but all, in his hands, led towards a central idealism. His work consisted in pointing out the various avenues of approach to the temple of idealism, rather than in unveiling its mysteries.
(my underlining added)
Just in case that page goes away here's a clip: