Fortunately, Calum's got well-informed parents who are providing him with supported opportunities to sign, to access sound, to interact and learn with deaf and hearing alike in an environment filled with resources specific to his needs. For those who claim to support a full-toolbox, deaf-specific education with peers, visual support for learning, and a family that is eager to adapt to the learning/language needs of a deaf child, I'd think you might find Calum's situation a picture-perfect example of the ideal, rather than something to disparage as "experimentation" or based in audist thinking.
My child's ongoing experience as a deaf child differs enormously from that which anyone here encountered in the past, and so will Calum's experience differ from Li's, but if you do pop back in, Calum's Mom, I wish you so much happiness as well as the same satisfaction we've had in finding a brilliant bilingual (sign and spoken languages) academic environment tailored to my daughter's needs and filled with peers and empowering role models, and the delight of watching a child bloom with fluent and full access to language -- in our case, thanks to a wonderful ASL-immersive environment and amazing bilateral CIs, the little one is happy, healthy, and age-appropriately fluent in sign and spoken languages.