technically, any-non official anything means you're still soft-modded; but i don't think that answers the question you're really asking here....
if he used modmii to update (or knows how to do any non-Ninty update), then you should still be fully softmodded assuming he followed the update with a priiloader install...
but let's assume he did the official update. then you lost the following: any non-maxed versions of 222, 223, 224, 249, 250 (as stated above). you also lost priiloader....(any system menu reinstall such as this effectively removes it). you lost bootmii@boot2 (if you had it and were on boot2v3 or less) and possibly bootmii@IOS.
...if i were you, i'd just fire up Modmii and run the wizard....tell it you're virgin 4.3, then skip the HBC install (you still want to run the hackmii installer to install bootmii...which can be launched from HBC as an app if you configure the folder structure correctly)
...TBH, it's kind of a shame you didn't have the 'disable updates' hacks in place before 'your brother' updated...