You both are right in my view.
They do need to be presented with fruit and vegetables and encouraged to eat them.
He is right that a 'battle' is the absolute worst thing you can do if you want them to have a healthy relationship with food in the future.
It's interesting that you've put fruit and vegetables together as normally kids happily eat fruit as it's sweet and are more cautious about veg.
Our daughter bankrupts us with the amount of fruit she eats- It can be pricey this time of year but have you offered them a choice of fruits rather than just say apple, banana, orange?
Vegetables can be tricker and for our DC it's the texture rather than the taste she doesn't like- so it's blended into pasta sauces, mushrooms into stroganoff, chilli sauces, curries etc so she is still getting the nutrition and taste.
Every meal is then also always offered with a sweetcorn/ peas/ baked bean side as they are generally 'safe' options.
You can talk in a age appropriate way to each child about the nutrition our body needs.
Also offer a daily multivitamin to each.