which only consists in copyig his files in the OS2 directory
Well... If you upgrade the OS later, then there may be one copy in your OS2 directory, a different copy in my eCS directory structure, yet another different copy installed by an user in a PATH directory, and yet another installed copy in an ArcAOS directory structure.
That's why an author of an "OS component" could consider releasing that OS component as an upgrade for all brands, unless the component is too new. Then it doesn't really matter if you are using a German eCS 2.x, an Italian eCS 1.x or an informal Korean OS/2 Warp FP, and you don't have to browse through your Spanish Warp 3 system directories to avoid the loss of a great tool after an upgrade to ArcaOS 5.1.4 ES.
AFAICT eCS (2.x only) saves TOP files in 2 directories, so when nothing but OS2 would be used then you've also moved the docs to that different directory. "OS components" could have a special status, and it makes using such an utility more common. OO.EXE is more stable than a matching Rexx script, but you may have to explain where to find it and how to install it.
Anyway, you can save TOP in the OS2 directory, but you may end up with sevelar installed versions of TOP, and you may not be able to find a manual someone refers to in a eCS subdirectory, which you may not have. Save it where an OS upgrade would save it. That may be OS2 directories, plural. Or ECS directories. Or ...