They basically imply that Jiraiya would be a fair match for the 2 of them. Considering how early in the series this is, its unknown how many of their overall jutsu's Kishi had worked out at that time. Having the sages with him, Jiraiya would be very resistant to Genjutsu as opposed to a normal shinobi not to mention his fighting strength. On the other hand, Kishi might not have thought of things like Kisame's fusion with his sword or Itachi's Susanoo (ie the exact power of Susanoo, because it was very likely he had already determined he would use that mythology for the name).
Bottom line is that without knowing exactly what kind of power scaling the 3 had at that time, we cannot determine how they would have stacked up against one another. However, considering everything, we can possibly say that Jiraiya could be a match for both of them at the same time given all his advantages, ie the 2 sages, SM and possible summonings, so I don't see a problem with it.