La traducción correcta es la combinación de ambas :

Que le dirían ( ustedes) o diríais ( vosotros ) a ese hombre.

El uso de le es necesario , otherwise is incorrect ...

The Google translation that includes "le" is correct. In Spanish, you will find apparent redundancy. I say "apparent" because while it can seem weird and repetitive to non-native speakers, it's a characteristic of the language and makes sense to native speakers.

It doesn't sound natural to omit the indirect object pronoun (le) even if you mention to whom you are saying it ("a ese hombre"). It <em>is</em> possible to omit "a ese hombre" (in the case that it were already clear who "le" refers to) but not the "le". It's one of the features that is particular to Spanish and differentiates it from closely related languages, for example, French, in which the use of an indirect object pronoun doesn't come with the same redundancy/repetition.

Le es un Pronombre personal átono... you don´t want to know that grammar part , but this is something that even Spanish speaker get it wrong specially people from Madrid ... muppets .

This error is called Leismo ...etc.

To make the story short Le reemplaza el objeto indirecto .

En español usamos <em>me/te/le/nos/os</em> para sustituir a la persona, por ejemplo 'me gusta', 'le gusta', 'te gusta'.

Cuando decimos 'le diríais' it means 'vosotros le diríais a él' so 'le' represents 'that man'.

Por ejemplo, If you say: <em>¿Qué diríais sobre este tema?</em><em> (what would you say about this topic?) </em>

Here you dont say 'le' because you are not saying something to somebody, there is no subject. Yo just use this personal pronouns when the action goes to somebody.

I hope this helps ;)

Hola Guyomar!

This feature applies to both direct and indirect pronouns, si?