Molten silicon is not explosive or particularly flammable. Its a metaloid that when exposed to air will oxidize back to the silicon teraoxide that was the original source of the silicon. SIO4 is commonly referred to as quartz sand one of the most abundant and chemically stable compounds on earth. This is all hyperbole as the system is sealed and only the heat is used across sealed heat exchangers. People deal with large quantities of much more reactive molten metals every day all over the world on a scale of hundreds of millions of tons per year mainly aluminum, magnesium, sodium, lithium all those metals are produced as molten in multiple tons per run quantities. Humans mastered dealing with molten metals in the bronze age before Christ was born.
Oh I am well aware of the properties of silicon. Spent 20 years in semiconductor processing. My concern is the use of this technology outside of a controlled environment by untrained or unaware persons. Your examples are all processes that take place in controlled environment(s). I think you would agree that improper of inadvertent handling of this “battery” could get people seriously injured.
I witnessed two events where polysilicon was released into the human space while it was in a vapor form in an explosion from leaking process gases. The toll on the operator in one case was life changing.
Machines fail - people get hurt. The cutting edge often does.