in A19, used to be able to change:
urn off Trader invulnerability and Teleport data/prefabs
trader_###.xml
change <property name="TraderArea" value="True" /> to False
change erty name="TraderAreaProtect" value="20,0,20" /> 0,0,0
Doing so now, does allow destroying of the trading post and wont teleport, but the Traders in them only give out dig quests. No other quests.