We live under Christ's government rather than man's and though in the majority of matters we obey the law, we can't do so in the cases where the state attempts to prevent us in matters of faith that we are beholden to under the Covenant.
For example: we have to share the Gospel (Mark 16:15; Romans 10:13-14): we have to give in charity (1 John 3:17): and live charitably, we can't commit heresy, we can't deny Christ before men, we have to meet together with the brethren (Hebrews 10:25) and so forth.
2 Timothy 2:19 ESV
"But God’s firm foundation stands, bearing this seal: “The Lord knows those who are his,” and, “Let everyone who names the name of the Lord depart from iniquity.”
When there's a conflict and your conscience is siding with God's laws (like sharing the Gospel) we follow God's law. We follow mans law for peace with men but in the end, it's Christ's government we are beholden to, not man's, even if it means our livelihoods etc.
In real public health events it's good to listen to the state and consider the real circumstances of the time, what the state says carries real weight for us. At the same time, we have to place all of God's law in a position of preeminence as well, the scales are there, in the whole of our responsibility to the Covenant according to Scripture and reason.
I always thought what they did was right for them. They shut down at first like everyone else and weighed the situation in their area against the rest of God's law and as time passed they followed their own conscience in the situation.
This is all we can do. We take each and every situation as it comes and do our best to do what God would have us to do, and every situation is different.
It's not really one size fits all, for example when MacCarthur was opening, other churches elsewhere may have made a different decision by necessity of their own areas circumstances.
Just my opinion, but in general I think this is what is right, just weighing each situation as it comes in light of Scripture.
There will be more and more times now that we face these situations for the first time ourselves, unless of course our societies become reasonable.