That's simple - the "wouldn't exist" means it wouldn't be possible to have it even for US users. There is only one build of avast!, one installer - and it's not going to change (it would make many things rather complicated, both for the users and for us). Therefore, there has to be, and will be, checks for installed features inside (be it the various shields, language modules, Sandbox, SafeZone, firewall, antispam, webrep, Vista gadget... or anything else). It's the same as checking for the version of the operating system - that's also done on every start (instead of having separate installers for Windows 2000, Windows XP before SP2, Windows XP after SP2, Vista 32bit, Vista 64bit... that would be crazy, and you might have to uninstall and install a "new" product after updating your service pack, for example). Or, checking for the installed programs (Is Outlook installed? Fine, let's use the mail-scanning plugin. Is the filesystem NTFS? OK, let's use the persistent cache. Etc...)
The thing is that the mere considering such a check a problem is kinda ridiculous. The program performs thousands of similar checks on every start, new virus definitions regularly add operations that are orders of magnitude bigger and slower than that... and nobody notices. So this common one-microsecond check can hardly fit the MIB analogy, as you aren't bothered by that, and actually have no way of telling whether such a check has happened.
So this is not "fighting hard to leave the code inside" - it's fighting against doing a completely illogical thing (from the programming point of view) which would take effort to implement, increase the complexity of the code (bringing some more bugs), increase the size of the code - and in the end, the result would actually be exactly the same as it was before, just with one additional checkbox visible somewhere.
As for the "bad feeling"... well, not sure what to say about that. I'd probably just point out that the antivirus already checks files on your disks for malware, redirects and scans your network connections for malicious code, checks your e-mail... which is where the sensitive data really are, and nobody seems to have a problem with that. Yet a simple feature which does nothing at all when not registered, and when it is registered it only receives data, doesn't send anything anywhere... is suddenly a problem. I mean, we are trying to protect your data, not to compromise them... but if we (or any other antivirus or security program you might have installed) really turned "to the dark side" and wanted to harvest your private data (or whatever else that this bad feeling might include), it would be rather stupid to add a new suspiciously sounding feature to do that - when all the necessary mechanisms are already there for years.
Anyway, this is not my "decision" (and my work also doesn't include this particular feature), it was just my attempt to explain the technical background (i.e. basically a personal opinion of somebody who knows a bit about avast! internals). However, since it doesn't seem to be going anywhere, I suppose that's the last input from me on that topic as well.