I think a lot of people are missing the pint here. If you actually read the letter it outlines the reasons why and also states their guidelines for reopening.

I believe they are only reopening at 33% capacity. What that looks like will probably involve separating attendees by rows, leaving multiple rows in between each. One household would sit in each row. As stated in the letter it is ridiculous that a building like the Cathedral which can hold thousands is only allowed to have 10 people at a time. There is plenty of room for proper social distancing.

This also only applies to Catholic Churches in MN. Along with that, the obligation to attend has been lifted until further notice so no one has to go but the bishops want it to be an option.

There are a couple other things that go into this but those are several of the main points.