Why would it have been wrong to write
Li2SO4 as lithium sulfur oxide?

Due to pyro-electric properties and molarity Li2SO4 cannot be written as lithium sulfur oxide.

Explanation:

Lithium sulfate is a white inorganic salt with the formula Li2SO4. It is the lithium salt of sulfuric acid.

Lithium sulfate has water solubility, though it does not follow the usual trend of solubility versus temperature — its solubility in water decreases with increasing temperature, as its dissolution is an exothermic process. This property is shared with few inorganic compounds, such as the lanthanoid sulfates.

Lithium sulfate has pyro-electric properties. When aqueous lithium sulfate is heated, the electrical conductivity also increases. The molarity of lithium sulfate also plays a role in the electrical conductivity optimal conductivity is achieved at 2M and then decreases.

Lithium sulfate has a rapid gastrointestinal absorption rate and complete following oral administration of tablets or the liquid form.

if you're asking what comes out, it's steam.