That comment was pretty unfortunate. When I heard him say it, I thought the same thing and wondered why minorities are any worse at using the internet than the rest of us.
Economic opportunities, is my take. You and I can afford our internet access, some in low-income areas cited, cannot, or cannot to the same degree as we can. Notice too that he didn't say "minorities" but "communities". The fake headlines love to obscure that.
He should have put that a lot differently, imo. Just saying "We're also making sure everyone knows how to register for a shot" would have worked just fine.
I may have the internet, but I didn't even know the process was online, and I'm sure when it's my turn, I'll spend tense, confused hours trying to figure it out. I like telephones myself, with a real human on the other end.