Did Alderdice ever really exist?

Ian Paisley made an odd point of order yesterday. Alban Maginness pointed out to Willie Hay that Lord Alderdice made a ruling that points of order should not be made during a ministerial statement, or during questions on it. Paisley then said:

On a point of order, Mr Speaker. Will you give some consideration as to how long the rulings of previous Speakers abide? Are those rulings eternal? Do we hold forever to the rulings of a person who sat in the Speaker’s Chair but was never elected to it by this House? Does there come a time to say “Amen” to those rulings and bury them?

In the unlikely event that Hay comes back and says that all precedent is out the window with the election of each new speaker, as seemingly requested by the First Minister (at least in his first two questions), it could make life quite interesting in the Assembly. Does Hay not have the power to simply change a ruling made by a previous Speaker as and when he sees fit?