It depends how "work" and "mining" are defined in this context.

In PoS, as in PoW, security comes from computations done by network participants. For example, in Algorand, nodes generate a proof that they ran a lottery with the correct seed. That's still work, is it not? Does it matter that it's more efficient work than the work that is done to maintain the Bitcoin blockchain? Can someone formulate an argument as to why this should be excluded from the definition of "mining"?

Without rigorous technical definitions, the result may just be that PoS networks adopt terminology like Efficient PoW and Efficient Mining.