The lock is in the radio part of the phone, a seperate processor and firmware, accessible through a radio interface (ril). GPL doesn't apply here.
To avoid having to deal with blocked AS, you have to monitor and control you customers. I scan all my ip addrs daily in the populars dnsbls. If a user gets listed, block direct outgoing mail (automatically), tell them to use the (scanning) smarthost and offer services to fix the source.
My (receiving only) mail cluster is in the backscatter dnsbl. since I like to do sender verification (with result caching) . This hasn't affected my outbound machines/AS in all these years.
SV is only to be used for scoring, there are enough legit retards out there without valid from or misconfigured BATV setups to cause false positves when you use it for immediate rejects before data.