Maybe it has something to do with "Notwithstanding paragraph (6)"
“(6) NO EFFECT ON CHILD SEXUAL EXPLOITATION LAW.—Nothing in this section (other than subsection (c)(2)(A)) shall be construed to impair or limit—
“(A) any claim in a civil action brought against a provider of an interactive computer service under section 2255 of title 18, United States Code, if the conduct underlying the claim constitutes a violation of section 2252 or section 2252A of that title;
“(B) any charge in a criminal prosecution brought against a provider of an interactive computer service under State law regarding the advertisement, promotion, presentation, distribution, or solicitation of child sexual abuse material, as defined in section 2256(8) of title 18, United States Code; or
“(C) any claim in a civil action brought against a provider of an interactive computer service under State law regarding the advertisement, promotion, presentation, distribution, or solicitation of child sexual abuse material, as defined in section 2256(8) of title 18, United States Code.
> "(C) fails to take an action that would otherwise undermine the ability of the provider to offer full end-to-end encrypted messaging services, device encryption, or other encryption services.”
My guess is no since even with a key escrow scheme the messages can still be encrypted end to end. Its just that there is another party which may be able to decrypt it later.