I don't disagree with your politics.
I disagree with your etiquette.
Your host was trying to do a good thing for his employees,
and you called his integrity into question in front of his guests (whether he actually heard you or not).
Imagine you throw a party in your home.
One of your wife's girlfriends brings a date.
The date makes a comment to the effect "what a dump".
Even if he's right, he's out of place.