I think your email was great. You needed to tell people that, as their manager, you would not place "getting to work on time / at all" over their safety.
There are plenty of people who might need that reminder, if they've had bosses that demanded they come in to the office in the middle of something dangerous.
Not every group email can be tailored for every person, so try to get a thicker skin. And feel free to say that ("not every group email can be tailored to every person's communication style") to the person who complained.
And the person who complained? I bet if you think about it a minute, you'll realize this person is generally a complainer, and you should just almost always subtract about 80% of the "oomph" from anything they say.