This article is quite odd: income appears to be taxed "more progressively"...One justification for this is that investors risk losing much or all of their capital. Workers, on the other hand, are guaranteed their wages This is not the primary justification at all, and I'd be rather surprised to see many economists arguing it. The actual reason capital should be taxed less than income (specifically, at 0%) is because…
The inflation problem could be mitigated with a structure that takes this into account.
I can think of other reasons that low capital gains taxes are good, like encouraging investment, but the "taxing savings" argument doesn't seem like it works.
IMHO what we really need is a way to distinguish rentier income from investment income derived from investing in growth. The former should be taxed as income or maybe even higher, while the latter should be taxed at a lower rate or not at all.