There is a difference between a suite and a theme.
A Theme contains the actual skin files them selves. This should only be done by the author.
However, a suite is essentially links to the skins. So the original author will always have their name attached to their skins. My suggestion is that if you are going to create a suite that only contains skins by a single author then don't do it. Leave it up to the author to do it or write to the author and ask permission. The suite is intended more for creating a general theme from skins from more than one author. So lets say I wanted to create a them by using a WB Skin by Koasati, a Logon by MikeB, a DesktopX theme by BoXXi and a Wallpaper by Nuvem, then you would create a Suite. Its not necessary to get permission from the authors. You can ask of out common curtesy but its not necessary.