I was reading the fifth troopers article on clan wren and it said to have cassion turn into an operative to promote clan wren to a commander so they cant be force choked is that true? just wondering

yes that would be correct.

When Clan wren get promoted, they become a commander unit and are no longer a special forces unit, including swapping out the SF command token for the commander token just the same way you replace Cassian's commander token with an operative token.

As force choke cannot target any mini in a commander or operative squad the commander Clan Wren squad is safe from being targeted by the ability by a mini with the force choke upgrade