"You are not required to use your Real Name to use the Service provided by Google. However Google makes no assurance that your true identity cannot or will not be disclosed even if you make use of a Pseudonym to use the Service."
... or words to that effect in the TOU would address the matter just fine for most people. For those who truly require military/intel grade anonymity, there are alternatives. For those who just want to engage with the general public without revealing their real name to all and sundry (absent hacking or subpoenas), the above should be sufficient.
If Google wish to go the extra mile and provide assurable anonymity, that's another matter.
Otherwise, this is a case of the perfect being the enemy of the good.
"You are not required to use your Real Name to use the Service provided by Google. However Google makes no assurance that your true identity cannot or will not be disclosed even if you make use of a Pseudonym to use the Service."
... or words to that effect in the TOU would address the matter just fine for most people. For those who truly require military/intel grade anonymity, there are alternatives. For those who just want to engage with the general public without revealing their real name to all and sundry (absent hacking or subpoenas), the above should be sufficient.
If Google wish to go the extra mile and provide assurable anonymity, that's another matter.
Otherwise, this is a case of the perfect being the enemy of the good.