A more careful wording might have been something to the effect that the writing reflected different sides of his character, which isn't unreasonable given he was in a totally different context and time of life.
I do agree with the theme of @CorporalClegg's argument that strictly observed structure and continuity between series (or even episodes) is not necessary for the show to achieve it's goals and can, in fact, be detrimental if it stifles creativity. The real universe looks very different from the perspectives of different individuals and contexts, the much larger fictional one that Star Trek is set in moreso and that word "fictional" is key here. Telling fictional stories to entertain is the primary goal of the show, not creating an immersive alternate reality.
There is no need to visually tie anything from other series into the show. It might be desirable if the viewers gain some measure of satisfaction or emotional connection from the familiar, it may even help to pacify some of the complaints about the subjective nature of the show, but from a story telling point of view it is not a necessity and definitely should not become a constraint.
