I mean... Maybe? But Intel proved their success of owning fabs throughout the 90s and 2000s, only 20-30 years after that statement were Intel even considered to be possibly dis-advantaged by owning it's fabs. But that was also a very different market.
So I don't think it's as direct a link as you seem to claim. Maybe it was the right decision if AMD had the money to keep it going. But it will likely forever be one of those questions that has no solid answer either way.
Intel had the margin and volume to be the exception to the rule, meanwhile Qualcomm, Broadcom, and a ton of other fabless design firms were making good money unencumbered by the risk of investing in a fab division, and with the ability to switch to the best fab for each chip at a given time.
He said this some time in the 80's to early 90's as a defence for their expensive commitment to still be running their own fabs when most big semi companies like Motorola were selling off their fabs and going fabless because it was eating their resources and it was impossible to compete with the likes of TSMC on node shrinks and value.
So even without Intel screwing with them in anti-competitive ways, they could not have kept their fabs competitive much longer. The writing was already on the wall way back then but Jerry Sanders was just being stubborn.
[1] https://archive.is/igC4r