Can any liquid food be beaten into a mousse?
Chocolate is a solid at room temperature, strawberry puree is not, so I strongly doubt that the strawberry would result in a foam.
The reason chocolate would form a solid foam is that it is largely composed of a two substances - sugar and fat. Together with the air these can form a solid of fats (similar to whipped cream) with microscopic sugar crystals helping keep it in place.
The only thing a strawberry puree would have that might reach similar consistency is the sugars. If you were to heat to a high enough heat that the sugars polymerize crystallise (like in candy), and whisk, you might get a structure like a mousse, but it would be crunchy.