I find the guy's comment rather amazing, frankly. If your query returns more than one row and you've written the PL/SQL proc with the assumption that only one row will be returned, the use of a cursor will certainly avoid the exception.
But ... in doing so it will be masking what is very likely a buggy query! This is not good! The query writer in this case has either miswritten the query or didn't understand the datamodel or the data contained within it.
PG does support cursors, BTW - it is PL/pgSQL which doesn't. The current, eventually-to-be 7.2, version of PL/pgSQL actually does but the version of PL/pgSQL contained in PG 7.1 and previous versions do not.