The "lookout" app does not claim to be anything like an anti-virus app.
The "virus barrier" app was apparently a thing that will scan for nasties in e.g. email attachments; it looks like you would choose to "open in..." their app from e.g. the mail app, and it would tell you if it found something matching its signatures. So it is also not an anti-virus product in any conventional sense. Not sure what Apple's objection would be. Have a look at: http://www.intego.com/mac-security-blog/virusbarrier-ios-8-antivirus-malware-scanner-iphone-ipad/ :
"For instance, email is one of the most common sources of malware in iOS. Once you receive an email attachment, before you open the file you could scan it in VirusBarrier to make sure that it is not infected with malware. Here’s how easy it is to scan these files:
Hold your finger over the attachment until the share sheet pops up
In the middle section of the share sheet, select “Open in VirusBarrier”
The VirusBarrier application will open and perform the scan
If no malware is found, you can return to the email and feel safe to open the attachment
If the scan comes up clean and no malware is found, our integrated file reader will open the document for quick and easy viewing, or you can send the file to a remote location, such as Dropbox, for storage.
*All scans must be done manually; automatic scans or real time scanning are not possible due to Apple restrictions. You may scan entire cloud drives and websites, but email attachments must be scanned individually."