My guess as to why nintendo is blocking (at least trying to) all free useland entrypoints (being browserhax,theme hax and ironhax) is that, with those FREE solutions you can achieve userland code execution (being the HB launcher and all homebrew in our case)
And if you are able to get userland code execution, when a arm11 kernel exploit pops up out of nowhere (it is litterally bound to happen, as long as people keep looking for flaws in the 3ds, flaws leading to arm11 kernel access will be found, and once you have arm11 kernel code exec, any further countermeasures from nintendo are useless, for reasons I will not discuss
This is why they are fixing any free way to execute code for as many firmwares as possible, since an arm11 kernel flaw Is bound to apear sometime in the future, they want to at least prevent most of their userbase from having access to piracy for free (no, this doesn't mean that an arm9 exploit exists for 9.3+, I have no idea about that matter and I can't discuss the "piracy for free" matter anyway) (believe it or not, but most people give up on piracy if they need to buy a special item/game to access it) and in my opinion the retro ban of the 3ds browser was a master move, GG nintendo for that booby trap. Also on a side note, they made a second masted move, any game cartridge with 9.9 or higher update contains a "dummyspider" this is simply an empty browser that will keep telling you to update sais browser to be able to use it, so DO NOT UPDATE TO 9.9+ with a game cartridge (triforce heroes being one of them) if you want your current browser hax to work.
(Boy, this was a long post and I'm not even sure most people will get what i'm trying to say, but whatever.)