That's good advice.
I read something about produce that applies here too. People thing fresh produce is waaaay better for you than frozen.
Guy from a retailer broke down how many steps 'fresh' produce takes to get to your store. Summarizing:
One day to pick and pack the item on site.
One more day to be shipped (typically by truck) to a warehouse distributor.
Another day to be shipped to your individual city/grocery store.
One day for the store to receive and catalog the goods, then put them out on the shelf.
That's already four days in most ideal scenarios from being picked to getting into your grubby little hands.
Conversely, most frozen vegetables use the same method of flash freezing the veggies at the height of nutrition and tend to retain that nutrition longer.
Now it's just down to how you cook them. If you steam rather than boil with water, frozen vegetables can actually be good for you comparatively.
Personally, fresh vegetables always taste better to me and that bias makes me think they're better for me. Until you find out that washing some types of lettuce and other fresh greens will never remove the pesticides on them no matter how long you do it for. Same with removing the E-coli bacteria.