Assuming randomness (no structure) should be the default position, except in the three cases I outline.
To adopt Russell's teapot analogy:
If I were to suggest that between the Earth and Mars there is a china teapot revolving about the sun in an elliptical orbit, nobody would be able to disprove my assertion provided I were careful to add that the teapot is too small to be revealed even by our most powerful telescopes. But if I were to go on to say that, since my assertion cannot be disproved, it is intolerable presumption on the part of human reason to doubt it, I should rightly be thought to be talking nonsense
i.e. we cannot go around suspecting periodic behaviour unless we have evidence, especially in a dataset as short as 35 years.
If you can't show that the apparent periodicity fits the three criteria I outlined, the default position
must be that it is an accidental outcome of stochastic process, if it is due to interaction or modulation of other periodic processes this must be shown, although this latter point is a possibility I unintentionally omitted from my previous comment.
But our default position cannot be that there are true periodic processes everywhere. Arguably there is but one true periodic process - the Earth's relationship with the sun. Aside from that many processes claimed to be periodic are in fact pseudo-periodic with a stochastic element, e.g. ENSO. If you want to show they're real (like the teapot), you must demonstrate that, the default position must be that they are not there (like the teapot).
And yes this applies to exo-planets, until there is evidence of their existence, or mechanistically based reason to suppose they exist, setting off on a one-way mission to colonise one is idiotic. Just because they are then found does
not disprove the principle.
If fairies are found to exist that does not prove the existence of god, ghosts, or indeed teapots orbiting the sun.