The overall context of Isa 43:10 says that Jacob and Israel had witnessed God. These chapters do not say that Jacob and Israel were going door-to-door giving out witness statements. These chapters say that even though they had witnessed YHWH, they had not called on Him (Isa 43:20-24). For that reason, God had brought them to the low state they were experiencing (Isa 43:26-28, Israel's destruction and Judah's captivity in Babylon).
It is interesting that Isa 43:10 says that his "witnesses" were his "servant" ("slave class"???).
Rutherford shackled the organisation with his "Jehovah's witness" legacy. Not only did he use a verse that is completely irrelevant and damaging, but he has prevented the JWs being able to break free from this word "Jehovah", which was invented by the Catholic Church in the 13th century.
Doug