He likewise introduced a certain show of liberty, by preserving to the senate and magistrates their former majesty and power.
Suetonius often does this; he seems to have 2 independent commentary's happening with each Emperor - one good, one bad. Fair enough - so this is one of Tiberius' qualities - he did, do some good stuff. He just didn't want to be in Rome, didn't want the job, was a nasty deviant bastard and was a totally miserable sod. Mentioning positives is a bit like congratulating Mussolini for getting the trains to run on time!!