It's not interpretation. That's literally what the word "replacement" means when used in this manner.
When you describe something as a "[thing] replacement" or a "replacement [thing]" you are describing it as an item that is not the original but substitutes for it and is less ideal for the task. A bus replacement service isn't a train and a neuticle doesn't make testosterone and sperm. These are things that replace the original and are used as a less capable replacement.
You can also use the word "replacement" to mean an identical item. You break your phone and get a replacement, for example. That's a different context.
Dude... this is how words work.
If you used the wrong word and it's been pointed out to you, don't kick off for a page and a half, and moan "what are you going on about" at the person who's asked you a question based on the wrong word. Realise the mistake when it's pointed out, suck it up, amend your position and carry on.
If you are communicating the wrong ideas with the wrong words that's your problem. It's literally impossible to have a sensible discussion with someone who uses the wrong words, has a tantrum when questioned on it, denies even using them, defends using them, and then finally whines about being asked to use the right ones. And this seems like it's the fifth or sixth time this has happened with you so far this year.
I don't even know why you're having a go at me about it (again), when I was just pointing out to you why what you said lead to the discussion it did because you seemed all confused about it. It's because you used those words, for reference.
It is, but it's not cereal. Steak would be a cereal replacement - it does the same job (food for energy) at the same time (breakfast), but it doesn't do what cereal does. And this is actually a far better way to see what you did with fast food as "a replacement meal".
Since when did a meal need to be healthy and balanced to qualify as a meal? Where are you getting this crap?
No, it's nutrition. Also, apparently, English.