Maybe because he said he never tested it, and some see it as a get out of jail card if it bricks someones PS3 or they have to reformat. With him reminding you , him saying he never tested it.
Its not something I need, nor do I trust due to what anyone will do to get access to wide open hacked PS3's thats on your home or works network enjoying your files like one of the family. That's my reasons.
Convert NTFS to FAT32, maybe this is the directly way to help you solve your problem. Typically problem is PS3 is not support NTFS, haha choose NTFS to FAT32 Converter (aomeitech.com) this tool can help you finish the conversion. In case of you want to convert it back, it also can help you.