Yeah... that's awfully strange. I would suggest doing
• Gatherer's Gurdeon III (+5 Gathering)
• Gatherer's Guile II (+4 Perception)
• Gatherer's Gurdeon I (+3 Gathering)
• Gatherer's Grasp I (+1 GP)
You could also do as you suggested and use a T4 instead to max meld the whole thing in a mere 3 melds.
Ultimately, it's going to come down to market prices/availability, and how much you are okay with blowing up materia. Personally, I prefer what I've stated above, because blowing up T1 materia isn't expensive, and it eschews the need for a T4. As always, guides are more guildlines, rather than hard and fast rules. Do whatever works best for you.
It is worth noting that there's definitely at least one mistake in their list of melds though, since the gloves only hold +4 Perception, yet they have Gatherer's Guile II listed twice (which would add up to +8).