If we’re going to get pedandic, blood infiltration of the heart is a medical condition, usually called infiltrative cardiomyopathy. So you’re correct that the metaphor is better, but the literal meaning could be confusing.

I like the cereal bowl analogy because cereal is ostensibly its own thing. But practically speaking, you’d be silly to assume it won’t be consumed with milk. Like it could be, but the box advertises it with milk, and the commercials suggest adding milk, and everything about the cereal implies you’re going to add milk. Adding water would make you the weirdo, and assuming other people would add water would be absurd. Like suggesting Trump would make an attempt to build a bipartisan coalition. If that’s what you’re expecting, you’re not in touch with the reality we all share.

Water to a sponge? That might have the same issue since infiltration is still a thing, so maybe we avoid fluids for the analogy. Fans infiltrating the stadium? Clothes infiltrating a laundry basket? Now I’m just saying things I see around me. Let’s workshop it independently and come back in a week with ideas. No rush, we will have four years of this bullshit.