Shrugs. Released no official information. (Said 70 for the maximum odds on the official website previously, supposedly. Removed it later.) Would not know how to parse datamined information directly.
Presumes the one capping after 30 calls to be correct. Evidently debunked the 70-255 chain maximum odds data. Found
a video talking about it. Never explained why, however. Cannot definitively say one way or another, consequently.
Spoilered the different claims below, for those curious.
Calculated the odds of
not obtaining a shiny Pokemon in a chain of 50 using Claim 2's data.
(1 - (1/4096))^10 * (1 - (1/820))^10 * (1 - (1/455))^10 * (1 - (1/315))^20
= 0.9046
Fails to obtain a shiny Pokemon 90.46% of the time without the shiny charm.
(Alternatively: 9.54% chance of at least one shiny.)
(1 - (1/1366))^10 * (1 - (1/585))^10 * (1 - (1/373))^10 * (1 - (1/273))^20
= 0.8828
Fails to obtain a shiny Pokemon 88.28% of the time with the shiny charm.
(Alternatively: 11.72% chance of at least one shiny.)
Takes a while, even with the kinder odds.
Edit: Noticed something interesting. Lists Claim #1's odds on
Serebii's Sun/Moon SOS page and Claim #2's 30+ chain odds on
Serebii's Ultra Sun/Moon page. Adds to the murkiness of the information.