Maybe he is trying to make friends with the order civs.
He may also have calculated that World Ideology Freedom will affect more his Order/Autocracy rivals than him. It's all about numbers for the AI, after all.
I happen to have done that calculation in one of my games (not by choice at first). I miscalculated that this would be an "all Order" game as the three leading civs were wide and heavy on science and rather peaceful if extremely strong, and I picked it early myself, to my grief.
I had proposed it as WI when no one but me had one. But my three huge and strong friends went Autocracy, and I was fearing the chain denouncements and DoW coming soon. I switched to Autocracy to avoid that and the unhappiness from pressure I was getting (which mostly reduced my culture for SP by undermining Fine Arts), but I had bought many delegates and Order would most likely still pass.... I looked at the numbers and I finally voted Yea too... Two points of pressure were better than the 6 I had from the Autocrats... especially that they now would protect me from those two points.... I had very high happiness as Venice (+50) often does. My Autocrat fellows, however, did not. They found themselves at Dissidents or Civil Resistance for the rest of the game, almost always in the negative total happiness but above -20, so they never switched. That slowed their growth and thus the expansion of their science too, that slowed their will to expand/grow/conquer as they could go into Revolution if they did and that negated their Rationalism opener bonus (reducing their science ouput by 10%), and that negated the effects of Fine Arts by which 50% excess happiness is added to culture.
Perhaps the AI is able to make these calculations too. Perhaps proposing Freedom as WI was the resolution that benefited Venice the most, if picking Order helped its rivals more than itself. The AI often seems to pick its resolutions based on the harm it does others, perhaps because the benefits are not all that often bigger than the harm some resolutions can do to others, so the greater benefit to gain is with the harm you do.
I noticed the resolutions are often aimed at the human when you're in the lead, but when you're behind they tend to target either the civ's worst enemy or else the current leaders (I got used to significant leads as I played on King since BNW, but returning to Emperor I noticed the game evolves with significant differences when you spend most of it as a mid ranking or lower Civ).
He may also have done it out of spite. The AI seems to get a factor if other AI or you voted against its resolution previously. They tell you they'll go against your interests too in the future, and often their next resolution targets your directely (ban, embargo etc.). Presumably, this happens between AI as well. It might have proposed Freedom because one or more of the Order civs pissed him off in previous votes.
