I don't quite think you understand my point or I've not explained it well, I am prepared and have to suspend my disbelief for the drug to work and exist as the basic premise of the series and then by extension the other drugs; have to accept some element of unreality for pretty much any and every series, especially GB series, it's the suspension of disbelief. Everything then stays within relatively grounded rules with nothing too extreme or out there after that. Mihari learning to code, coding a robot with some AI or integrating one onto it, then building a robot all in one evening goes beyond the established norms and rules, it is jumping the shark. The drug also made Mahiro 12 at the start of the series.
I do get your point, but at the same time I think the limits on suspending disbelief are quite personal - I'm a coder/devop/sysadmin type, I always struggle when I see movies/etc trying to portray stuff like that; on the other hand, everything I know about police procedures comes from TV, so I don't bat an eyelid about most of the shit they get away with (unless it gets too egregiously ridiculous). Combine that with the fact that each person's reading of the background and setting will be different, as will how much the internal consistency of the setting matters to them . . . And, of course, whether or not any particular thing counts as "jumping the shark" is just as subjective (and is also something that can only really be judged in hindsight). . .
All of which boils down to something like "yeah, but that's just, like, your opinion, man" . . . Or, being a bit less snarky, I think you're being maybe just a bit unreasonably harsh on this chapter. It's not a
great chapter, honestly it's mostly just another chance to show how great Mihari is, alongside poking fun at her being a bit strange about her older brother, but it's mostly Just Another Onimai Chapter(tm). There's even a hint of toilet humour (even if it won't end up on the official list of pee-related chapters)!
But eh, everyone's got their own perspective on stuff, there's nothing wring with that leading to different opinions.