Yes, but your deduction is incorrect. They're saying the SAF are negative _and_ they recommend their personell to use the service, not that they are negative _because_ they recommend it.
I don't see how you can know that "because" is incorrect. This seems like it could be possible to me:
(Possibly) SAF is negative because they use Signal, and don't want a law that would introduce vulnerabilities into Signal that could be utilized by third parties.
(Possibly) SAF is negative because they use Signal, and don't want a law that would introduce vulnerabilities into Signal that could be utilized by third parties.