Sorry I cannot agree that such is a bug.
Such is the case only if you are a user that cannot decide to use icons or not.
Everyone knows that icons are packed inside the extension.
When inititally selecting the ondemand option, if the user uses icons, the icon is extracted by temporarily mounting the extension. The ondemand script is generated and its associative icon is stored in the ondemand directory. If the user does not use icons no such icon is extracted or stored. This is normal. So if the user laters decides to use icons none of the ondemand items are regenarated. This too is to be expected. What you are suggesting woulld be upon everyboot or upon load of wbar all ondemand items be regenerated. This would slow down the boot time as to void the main benefit of using ondemand, that is, much improved boot times.
Now if you argue that icons should always be extracted, then I would expect a "bug" report be filed as to why do I have many icons in the ondemand directory when I never use icons.
Bottom line, if you are a user and cannot decide where to use icons or not then realize that your ondemad items would only have icons when icons where in use.
Of course you can control the regeneration of any ondemand item's icon by using appsaudit ondemand maintenance to remove said item then immediately add it back as an ondemand item. Its icon will be extracted.
But I am not going to slow down the boot process that would penalize everyone only for the benefit of those who are fickle about their decision to use icons or not.