The order from the court was referenced on the link you referenced above. It's below the PDF of the original motion.

That's what I get for not scrolling all the way to the bottom.

Anyway, Heins may not be correctly summarizing the law, either. But as you allude, it's not crazy to interpret the statute that watchers/challengers should be allowed anywhere where voting takes place, not just on Election Day proper. I think that's also consistent with the general intent of the watcher/monitor regime that Missouri and all the other states have, and it's good public policy that the voting process be open to observers and monitors.

So I don't think this order is "judicially approved election interference." I think that the judge clearly just grabbed the pre-printed "motion approved" form rather than drafting a bespoke order, which created a bit of confusion as to what he was actually enjoining - but I think from the context of the motion, he's granting a temporary injunction forcing the County to allow watchers/challengers to monitor the early voting, if anyone wishes to do so. Which may be right or wrong under a deep dive into the language of the statute, but doesn't seem like an egregious thing to order based on a quick reading and the fact that there's only a few days until the point becomes moot.