It will still be protected from spam, because getblocktemplate and similar commands always put transactions from the highest to the lowest fee, so with those settings, free transactions will be included only if there is a room for them. And meanwhile, they could be combined with full-RBF, or they could even increase in fees, so that 500 transactions A->B->C->...->Z paying one satoshi each could be compressed into a single transaction with 500 satoshi fee.
The parameters are designed to prevent unnecessary resource usage by having to receive and relay these free transactions. While your mempool will still kick the transactions from the lowest fee once it hits the size limit, the mempool fee rate will still increase and overwrite your parameters.
If not, then your mempool will contain unnecessary transactions that wouldn't be mined regardless.