He isn't talking about users of bitcoin. he is talking about MINERS. Already mining is somewhat exclusive. Think someone living on a dollar a day with a 56k modem is going to be able to afford an ASIC? What he is saying is that rather than trying to cater to 100% of people who can mine... it's better for the bitcoin network to have the grunt work(mining) done by users with decent internet connections. (which already prevail in the developed world). Otherwise the bitcoin network can't succeed because if it becomes more popular... then the network itself will be a bottleneck.
Sheesh... When I brought up 56k modems, I stated quite clearly they are too slow to mine on, because the orphan rate would be way too high. However, they are fast enough to keep up with the chain, letting you
validate it and make sure some centralized cartel of miners aren't trying to rip you off via inflation.
For an acceptably low orphan rate, say 2%, you need a much faster connection that a 56k modem, because you need to be able to download a whole block within a about 10 seconds.