LSJ s.v. ἀνήρ ΙΙΙ comments:
"man, opp. youth, unless the context determines the meaning, as in οὔ πως ἔστι νεωτέρῳ ἀνδρὶ μάχεσθαι ἄνδρα γέροντα Od.18.53; but ἀ. alone always means a man in the prime of life, esp. warrior, ἀ. ἕλεν ἄνδρα Il.15.328;...".
Although this lexicon shows plenty of instances where the meaning given for a word in fact incorporates material from the context (see, e.g. J. Chadwick, Lexicographica Graeca (Oxford: 1996), 32-34 against 'only' as the meaning alleged for ἀγαπητός), this section of this entry at least shows an awareness of the issue: in Od.18.53 both ἀνδρί and ἀνδρά are neutral as far as age is concerned and so the former instance of the noun per se cannot be evidence for the meaning 'young man'. Age is specified by the adjectives: νεωτέρῳ and γέροντα.