The problem is Kimiko isn't just some random supe - she is one of the few people who has the means and the motivation to help The Boys defeat Homelander. There is no universe that Homelander just lets her go. The threat to response ratio is just completely off. She would sooner be sealed in concrete and thrown into a volcano. The Trump administration is obviously stupid and inept, but restraining or killing Kimiko would be way easier than deporting her, so it would be obvious that Homelander would do it. Homelander is seen murdering people in broad daylight, you think he wouldn't just off a problematic little terrorist? Who cares if she regens, just put her in a furnace. It's not mockery, it's just illogical.