Who knows, Pa seem to not know that Minato had Sage Mode. Since he compared Naruto Perfect Sage mode to Jiraiya and to Minato.Same way Naruto did. Toads.
Jiraiya cant maintain it. In fact, he cant do it since he cant enter to sage mode alone. Minato can, but not as much as Hashirama or Naruto.Probably jiraiya or the toads
He was able to do a perfect sage mode but not maintain it for long
Jiraiya had the chakra to maintain but wasn't able to perfect it
That's also why it was weak and pathetic.Last minute asspull to make Minato relevant.