Tomas,
I may have misunderstood your original question. linkTrackVars and linkTrackEvents are set to "None" on page load because on page load they are not needed. linkTrackVars and linkTrackEvents are only used for link tracking.
When utag.link or s.tl() is called, Tealium will only set linkTrackVars and linkTrackEvents to "None" if there aren't any values. The clearing of the variables happens *after* each server call that is made so every time SiteCatalyst gets called the server call is starting with a clean slate.
So to answer your question, Tealium already does what you suggest, but with the addition of clearing the variables after each server call to ensure data isn't being sent when it shouldn't. If linkTrackVars and linkTrackEvents were set to "None" before the server call was made then no variables would get sent to SiteCatalyst.
In your specific case, eVar11 is populated with a cookie value. Tealium does not clear cookie values after each server call, only SiteCat variables. Because that cookie has a value that is persisted, it contains a value each time SiteCat is called. Because it contains a value, our mappings will pick it up and populate eVar11 with the value of the cookie. Then because eVar11 has a value Tealium will auto populate linkTrackVars with eVar11.
Hope this helps clear things up.
Cheers!
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