How quickly do you think other miners will ignore your 'malicious' blocks?
If you've changed the rules to say that 64MB blocks are legit then they are not "malicious" by definition (they would be in accordance with the consensus rules) so they can't be ignored.
If such a malicious actor exists how does a 1MB block size limit stop them from attacking/destroying bitcoin?
Because everyone with even fairly average bandwidth and supporting hardware can compete to create the next block (which is what happens now).
The reason that SPV mining is used currently is to try and get a slight advantage that poor bandwidth would otherwise prevent.