The part about "changing the law" I'm sure is a result of the structure of the 1937 regency act, which was unusual in that it tried to provide for subsequent reigns as well as the one recently begun. Until then, each reign, which required it, had an individual act or bill to specify who would be regent for a minor sovereign. Almost all of these named the surviving parent as the designated regent. Because the 1937 act set up a procedure for future reigns, it wasn't strictly necessary for the present Queen to ask for a new act. It's quite understandable that she did so, of course; her confidence in her husband and a wish to have him as regent for their child, had the situation presented iself, is evident. It certainly wasn't revolutionary or unreasonable.
