1) Must be sad b*tards. The one who jumped me simply switched cans on me and then sat round. They may eventually have taken the ore -- by that time I had lost interest.
2) Presumably therefore are looking for PvP in hi-sec. In which case, it would be illogical to draw any conclusion than that they are fully ready for anything that's brought to them. If you show up in -- say -- a cruiser (because the can-switcher was in a destroyer), "they" will simply bring in a BS, and so on. The ore is simply a pretext for wanting to gank you, only they want you to Bring the Gank, so that CONCORDE won't intervene.
3) Can be avoided by not using a can. So, the theft is simply by way of an unofficial tax on hi-sec mining. Which given that someone was offering well above the market level for ore in my system, is a fair rebalancing of ISK.
4) Doesn't therefore appear actually to raise any real profit. To steal my can-load took (to my best estimate), the initial destroyer, which then stayed in-system for at least 45 minutes, and (presumably) a hauler to collect the can (unless they simply let it decay and abandoned the ore). I don't see how this makes any ISK of itself -- the time they were there, I could have mined just as much myself.