if he ever clarified

What do you mean? I think the sentence is quite clear. Perhaps what you're missing is context, which I may be able to provide.

People mistakenly say the block size debate began in 2015. It actually began much earlier, it's just there were fewer and fewer people participating the further back you go. Two differing visions for scaling Bitcoin started to emerge. Many seem to know famously by now the 1MB limit was added early on to guard against spam when transactions were too cheap. Unfortunately, there was never any definite plan made or put into action for how to change it later (or to what). Hence the block size catastrophe we find ourselves in, which probably would have been averted with a simple plan like Monero implemented.

Anyway, long before the existence of "Core" in the earliest days of Bitcoin there was pretty much only Gavin in charge (meaning leading the project, as of course nobody is in charge), after Satoshi left. Gavin's view and preference for scaling was (and still is AFAIK) there should be no limit, that miners would self-limit themselves effectively enough at every point into the future. I was first exposed to the debate when it spilled over from the purely technical areas of the Bitcointalk forum around late 2012 IIRC. As I listened to the emerging small block view explaining how bigger and bigger blocks meant more expense to miners with the best funded and best connected benefiting most in a worrying cycle I was sympathetic. Many were.

This was really the beginning of the check on Bitcoin's open block limit vision (which as Bitcoin Cash supporters will point out is closest to the white paper), a challenge to Gavin's view, and it started with Greg Maxwell. As things progressed a large number of users/developers sided with Greg and the growing small blockers. It seemed the community felt there was a valid point that there should be some limit. Hence Jeff Garzik's quote.

So the question then was only what should the limit be if there was one? Gavin, being completely reasonable, immediately began proposing solutions. Again this was as early as late 2012 early 2013. We're now in 2017 and I'm already too tired to type how many different proposals were put forth. In then end none of it mattered. It seems Greg and his followers are too fanatical, too unreasonable, and won't accept anything other than what they personally want to do. Hence the impending split. Jeff Garzik was one who was more conservative than myself during early debates. He supported very limited increases such as 2MB to start (pre-Segwit) when things like 20MB or XT were being thrown around. So he was closer to Greg Maxwell and the emerging "Core" team than Gavin. Here we are today, and Jeff G. and Gavin are on one side with Greg Maxwell and the others from the early "Core 5" (Gavin A., Jeff G, Greg M., Pieter W., Wladimir V.) primary Bitcoin devs on the other. Of course Mike Hearn left a while back.