A someone who is broadly sympathetic to the idea of labor ownership of the means of production, could I trouble you to explain what's so obvious about the stupidity of this plan?
Taxes on corporate profits are generally seen as reasonable in the abstract, and they're common all over the world. I could see setting an unusually high tax rate being problematic, but that doesn't appear to be what happened.
And it doesn't appear that the state was seizing anything. They were buying up shares off the public market. This doesn't seem more objectionable than any other hostile takeover. If a business owner wants to maintain control of their company then it's trivially easy for them to do so. All they have to do is not explicitly sell it, which is what an IPO is after all.
And I'm having trouble seeing where the creeping socialism concerns come in. The end goal, according to the wikipedia page, was that the companies would be owned and operated by their own labor unions, which isn't an uncommon or inherently controversial corporate governance model. The state appears to have merely been facilitating the transfer.
With perfect hindsight we can of course see that it didn't work out, but I doubt I would have been able to predict that in advance with any confidence. Would this have been fine if the state used a different taxing model? Would it have been okay if the labor unions managed to do it of their own initiative? Is it that broadening ownership of a corporation is inherently objectionable for some reason?
What am I missing?