[Grammar] Singular or Plural

A recent issue in Hongkong newspaper, someone said :
"It is important that our leaders write proper English which befits their status and sets a good example for our society."

However, the editor of the newspaper thought that it should be
"It is important that our leaders write proper English which befits their status and ***set*** a good example for our society."

It had been put into local forum and the vote was 50-50, so what do native English speakers think?

[David L.]

'sets'

1 (use of proper English)...which befits their status and which sets an example.

Otherwise
2. ...befits their status, and so set a good example for our society.
Here, 'set' refers back to the plural 'leaders'.

Without the 'so':
"befits their status and set a good example for our society" - a speaker could, by even emphasis on the highlighted words and tone of voice that renders 'set a good example' as a collocation, the clichéd exhortation, make this work. But the sentence is written: be kind to the reader and make it clear whether you mean (1) or (2) by the inclusion of 'so'.