You are fooling only yourself. Nowhere on those images it says Taiwanese is mostly the same as all Austronesians or that Polynesians are the same as Austronesians, but it is only true for opposite, where Taiwanese are (part of) Austronesians and also Polynesians are (part of) Austronesians. It would also help if you could understand what those colored bars represent.

Culturally Austronesian people nowadays include y-dna O(with origins in SE Asia), M&S(Papuan) and C(part of northern Sahul). Most of Polynesians share mtdna B, but it is completely different mix with rest of Austronesians.

Taiwanese aboriginals have 66% O1a, which is considered Austronesian, that originated in Southern China and which was in the cradle of Austronesian culture. Taiwanese aboriginals also have ~10% O2 and ~10% O3.

Hawaii natives have mainly C 34%, 24% O2 and 18% M

Maori have 43% C, 2% M, 6% O and rest is from Europeans. If the European ancestry is disregarded then share of y-dna C dominates with 85%. On that scope of "similarity", where Maori people are mostly the same as Taiwanese, they would also be very similar to virtually all of other people on this planet.

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Polynesia is mostly dominated by northern "Sahul C y-dna":

https://en.wikipedia.org/wiki/Y-DNA_haplogroups_in_populations_of_Oceania

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Even if they are speaking Austronesian language, people like Maori or Hawaiians are more related to people living in Timor and West Papua and to their ancestry those are more important than Austronesian ancestry - where only few of them in Timor and Indonesia are speaking their original languages and nowadays they are speaking mainly Austronesian. Culturally they are Austronesian now, but their history did not start in Taiwan, because they were inhabiting Indonesia for the last 50 000 - 60 000 years.

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TL;TR: Taiwan is not original genetical source for all Austronesian people - only culture and language, that was spread over already populated islands.