He does sound like a whole-language reader. I think that the better the long-term memory of a young child, the more likely they are to rely on it in learning to read in this way. It can be frustrating to them to learn phonetics, as it's not as amenable to quick recall at first and it feels like slowing down to them.
I used some whimsical
phonics flash cards with my older son way back when, to make sure he was getting the rules in place. We never really studied the rules intensively, but later on when I was teaching him to spell, we'd blast through up to hundreds of words on spelling lists at a time, slowing down to 40-50 in a quick session when we got to harder words. I'd take the time during those sessions to point out certain words and make sure he knew the rules at work, and the first time through the list would ask him to try to spell each word without seeing it first. This not only got him thinking about encoding and the rules, it let me quickly find out the few rules he was missing, and encouraged him to struggle to recall the spellings of words from his reading as well, another good skill for a speller to have.
