The small excerpt posted by Elon musk is from Yoel Roth's PhD dissertation "Gay Data", in which he argues Grindr's important role in gay culture, as well as how service providers, such as Grindr, should implement strategies to help connect queer young adults. Roth does not endorse young adults joining the app that is intended for adults, but does note that there are already some using the app. There is no evidence of Yoel Roth endorsing child sexualization in his dissertation.
"Even with the service's extensive content management, Grindr may well be too lewd or too hook-up-oriented to be a safe and age-appropriate resource for teenagers; but the fact that people under 18 are on these services already indicates that we can't readily dismiss these platforms out of hand as loci for queer youth culture. Rather than merely trying to absolve themselves of legal responsibility or, worse, trying to drive out teenagers entirely, service providers should instead focus on crafting safety strategies that can accommodate a wide variety of use cases for platforms like Grindr - including, possibly, their role in safely connecting queer young adults."
Roth, Yoel, "Gay Data" (2016). Publicly Accessible Penn Dissertations. 1985.
https://repository.upenn.edu/edissertations/1985