When those two were CEOs, many companies had their own fabs, including AMD. IBM. And too many others I can't even remember.
Intel made a lot more money than TSMC, and even TSMC commented how Intel could get much higher margins. Given we're talking about the 20th century, and how companies made money by using their fabs to get the best chips out there, it's not clear how this made sense for Intel.
Keep in mind, when the 486 came out, it was $1000. Yeah, in 1989 dollars. That's where the money was.
I don't see how TSMC would factor into anything. As an investment? Maybe. But, Intel had much better fabs and tech than TSMC, why would they want to buy them? What possible good would it do at that time.
Now, if you want to say Intel should have considered outsourcing much sooner than they did, well, you could make a really strong argument. I think the 20th century was too soon though, because the competition in processors was very intense, and the cost was crazy high compared to today. But, even NVIDIA said a long, long time ago that Intel should open its fabs for others. So, I agree they should have done it sooner, I just don't think 1995 or so was that time. The money was in selling your designs, not making other people's. But when it became obvious that silicon was going to be in all sorts of devices, Intel should have pivoted to that. But I think being an anchor investor in TSMC made less sense than opening up their own fabs, given how much better their tech was.