When elected officials decide that a Plattform/network is now part of the public space the owners loose out.
It happened to railways, telephone grids and all in all was an improvement.
If they implement a public service, freemarketers not unlike yourself will accuse them of unfair competition and spend their lives sabotaging them, like Murdoch does with the BBC in the UK.
The reality is that your position is effectively that nothing should change, and everything in this space is as good as it can be. The public at large clearly disagrees, and this is a step in the direction of addressing some problems that are extremely hard to deny.
Besides, nationalisation would be nothing new. There are laws in your country, whichever it may be, for the state to confiscate your land for the public interest. That's not trespassing, that's the power of the collective trumping other rights. This is not it anyway - this is mandating standards, like the size of your electrical plugs.
Mandating size of plugs is a good thing for anyone to build things that can operate with electricity, mandating some private entity with a perfectly functional ecosystem without any interest to open its system to provide a certain type of socket, is not.
Food is necessary for the public, but there aren't a lot of governments running their own farms. Or construction companies, power generators, or really anything else. The best possible system is where people create goods and provide services to each other, and the government ensures a system where this exchange can be fair and thrive. This is exactly what they are doing with this law.
Power companies are being created while there are rules so they know what they're dealing with.
What's happening here is someone created a platform, spent years building things, and now EU is coming and saying oh you HAVE TO open it up. Not even mentioning the mess about having different rules at different places (e.g. I can't send many things to people in the EU in Instagram DM).
This is plain wrong.
Their government decided what is allowed in their country.
If the companies don't like it, then they should have won the election, or they should leave and go do business elsewhere
