So if the sender does not up the fee a bit it will bounce sooner or later, and to what purpose was it sent then?
Was this done specifically to bounce eventually?
Or a SPAM attack on BTC with underfunded TXs that are meant to bloat the mempool?
The motivation for all these "mempool attacks" don't make any sense to me. You just temporarily hold up the mempool from processing other transactions for shits and giggles. Eventually the mempool clears because you cannot keep creating spam at this rate forever, and all of the transactions get processed, making the whole attack useless.