The issue is that pure cash does not use time, but the smart layer requires that bot activity eventually terminate or be re-thumb printed. Pure cash allows the possibility that a trading bot simply finds no advantageous trade, even though it runs with a finite transaction count. Smart contracts require some specifies set of trades, or timeout, come to completion, because smart contracts always have grandfather's clock.
How do we locate a bot that is complacent past its time? The secure element has to do that. The secure element needs to connect up to the pure cash net at reasonable intervals, and manage its bots. A timeout means your savings/loans accounts have to be adjusted, or ledger service called; a sort of legal requirement that the human take a look every so often.
But move the management of timeout to the smart layer, actuated by secure element. The alternative is to have the pit boss check trading bots, or the ledger service has to check queues for timeouts on the queue. Not good, that is not the job of the pit boss, secure element manage their own bots.