That isn't any proof and it doesn't even say against what I said. It simply explains how the Juubi is created through the combination of all the Bijuu chakra and Gedo Mazo Statue. As in the Spirital Chakra and Lifeforce coming from the two sources. It doesn't matter how much chakra the Juubi jas on either part when we are talking about if they Bijuu's have gotten more chakra or not. If all the Bijuu's gained more chakra as a part of the growth they have gone through then the Juubi would have more chakra than it had during Hagoromo's era. Judging by the sizes, a complete Juubi in the current age would have at least 9 times as much chakra as the one Hagoromo faced. Even incomplete it has more chakra than the one the Sage defeated.
The Bijuu's are pure chakra, meaning that the natural chakra has no effect on them really. As that belongs to the Gedo Mazo Statue, so if they are larger, then they have more chakra. Another thing that can be provided as proof to this is that Minato sealed away half of Kurama's chakra, and as a result, Kurama became twice as small.