This is very upsetting. And the response clearly was copy pasted from a response to Firefox. As you can see:
At this time, HubSpot does not plan to build specifically for Safari because we are not able to bring a comparable experience to Firefox that we have for Gmail and Outlook. As we evaluate other enabling technologies like Google add-ons, we will revisit this idea in the future but for now we are not planning to build a Safari specific solution.