[FIX] TokenWallet: Assert a username

Follow up to Iccce554b5c9e83a42ae87c0bd69e38f880e3f6ac

Fixes another place where assert would fail if the
sysop username is different to the normal username.

Bug: T74238
Change-Id: I7c438e16d40ff7128980fd2eecf1575eeac40114