I know this is old but I have been recently asking myself this same question. I have concluded that yes kilning would count as processing since kilning is equal to fermenting or aging as far as the people here see it. But the definition is sufficiently vague to mean pretty much whatever TTB wants it to mean. This is one of those areas where you need to ask a lawyer or TTB or proceed knowing there is a risk of legal confrontation with ATF.
From the US code
www.ecfr.gov
Processed tobacco. Processed tobacco is any tobacco that has undergone processing, but does not include tobacco products. For purposes of this definition, the processing of tobacco does not include the farming or growing of tobacco or the handling of tobacco solely for sale, shipment, or delivery to a manufacturer of tobacco products or processed tobacco, nor does the processing of tobacco include curing, baling, or packaging activities. For purposes of this definition, the processing of tobacco includes, but is not limited to, stemming (that is, removing the stem from the tobacco leaf), fermenting, threshing, cutting, or flavoring the tobacco, or otherwise combining the tobacco with non-tobacco ingredients.