This is an excellent piece of strategic PR inasmuch as it refocuses the debate on the email issue (as is evidenced by the below posts), and obfuscates the real issue, which is that Instacart changed the terms of service and proceeded to charge people, something to which they never consented. Whether or not Instacart bothered to inform their customers about this fact is irrelevant; they shouldn't have done it.
From a customer standpoint, their actions are appalling and the apology is obviously unfulfilling and fails to recognize or rectify the true issue. But, from a business standpoint, this post is very strategic and effective at mitigating public outrage. Although I'm still upset by the choices that Instacart made, I can't help but appreciate the effectiveness of their response tactics.