It’s a weak answer but it depends on who owns the 50.9% and it depends what kinds of shares are held by whom. If one other person owns the controling majority, the government is just a nominal owner taking dividends.

Alternatively, a private owner could control such a company with just 1% ownership if they control the government in some way. Because all they have to do is get the government to vote with them and they have a majority. E.g. they might have the power to tell the government who to appoint to exercise any power that comes with the 49.1% interest. Or they might tell the government, vote with me and I’ll conduct XYZ infrastructure projects or support your election campaign. Or they might offer the person who does the appointing a seat on the board and consultancy fees. Or they might know that the person on the board is an ex-employee—who better to represent the government than someone who knows the company. Corrupt capitalists have a variety of methods!

States have other powers to intervene but doing so in 1984 would be a strange move, globally speaking; the anti-regulation fever had already started to kick in (I’m unsure whether India was neolib at the time but that doesn’t change things too much). It wouldn’t have to own a stake to exercise that power.

If a state can control companies without owning them, it means that state ownership is not the only way for states to control companies. Which means that state ownership does not explain anything in and of itself. I.e. state ownership doesn’t tell you that there’s socialism. It only tells you that there’s state ownership. Otherwise the mere existence of states means there’s socialism (assuming that state ownership = socialism because ownership = control). Maybe there are people who believe that but I’m unsure how seriously they should be taken because it’s an asinine view.

I suppose the person you’re arguing with is a western reactionary? States owning stock is not socialism. Just look at the aftermath of the 2007–9 housing crisis: capitalist states were buying up banks to keep capitalism running. The mere fact of state ownership does not imply socialism. The major factor is who controls the state: the bourgeois or the workers? And if the workers control the state, it’s socialism even without state ownership. State ownership is simply one tool that either a bourgeois or workers’ state can use to exercise power.

To get a full answer about Bhopal, you’d also have to look at the relationship between legislators, state officials, and the other company shareholders. To suggest that state ownership automatically equals socialism indicates a flawed model of state relations. It entirely ignores the fact that corruption exists. Then again, liberals think corruption is something that only happens elsewhere until it happens at home and then it’s an aberration notwithstanding that it’s constant.