Yes, a few PP have been suggesting that he might have strengths and weaknesses that appear to cancel each other out. You might not be able to see them as literal strengths and weaknesses, because what many 2e individuals do is work very hard using their strengths to compensate for their weaknesses, just to get an average product. Rather than having mental or emotional energy left to excel in their strength areas, they spend it all on buttressing their weaknesses, often using strategies that are much less efficient than their neurotypical peers use.
For example, learners who struggle with phonetic decoding ("breaking the code"), but have very good visual memory, may laboriously memorize the shapes of all the most frequently encountered words. Eventually, they build up a repertoire that is functional, and may even be able to read reasonably quickly, but are still stumped by novel vocabulary, especially if they haven't heard the word in their oral vocabularies. So they look like readers who started slow but caught up, until you challenge them with low-incidence or technical vocabulary. If they have strong enough visual skills, they may even manage to memorize the spellings, but usually, they spell much more poorly than they read.
Another common situation is individuals who manage to learn the rules of phonetic decoding, but have a deficit in attaining automaticity, which restricts them from reaching reading fluency. They often read very slowly, fatigue easily, and may lose comprehension in lengthier text. They also tend to read better than they spell.
And yes, dyslexia can continue to be a problem even after an individual appears to be reading within the average range, especially with regard to reading comprehension, spelling, and written expression, for some of the same reasons described above. It also can affect vocabulary and general language development, especially beginning from grade 3 or 4 and up, when vocabulary acquisition starts to shift from oral (environmental) sources to written sources. If reading is slow or laborious, or if comprehension is compromised, then the dyslexic learner may be exposed to fewer and less sophisticated words, with the gap in vocabulary widening year on year. In your DS's case, the gap, if there were one, would be between his acquired vocabulary and his verbal cognition, not so much between him and age-peers.
It sounds like your DS is using his higher-level reasoning skills to manage reading comprehension, even though his decoding skills are only average. This is a good compensatory strategy, and one he will probably use all his life, and suggests that the most likely significant complications would probably arise in written expression--of which he has probably not had much demanded, so far.
And, btw, some research has found possible benefit to re-training dyslexics to read using more cognitively parsimonious strategies than the ones they typically use. (More brainpower freed up for other things, like comprehension.) Though he is probably too old and too good of a reader to bother if it is not otherwise called for.
