Hajr of an authorized person refers to restricting a person’s power to trade or act after that person had previously been given permission. The information changes what the person is allowed to do going forward.
On one side, the person who granted authority exercises a right to withdraw or restrict it; on the other, the formerly authorized person is now bound to refrain from future transactions under the old permission. This is compulsion in one respect.
Timing matters. The discussion concerns future acts. One should not automatically declare every previous transaction void merely because a later revocation was reported. Prior acts and the effective communication of restrictions have their own detailed rules.