These are deliberate redefinitions of the term "Turing complete". The reasonable interpretation is that evaluating a single block can involve an arbitrary computation (if given enough gas). Ethereum has this property, Bitcoin doesn't.
These redefinitions say that you can take a few computation steps per Bitcoin block and save their state such that a later block can take a few more steps, so over time, very slowly, spread out over many blocks, Bitcoin can also implement an arbitrary computation. This is theoretically cute but otherwise useless.
The universe is finite so no Turing complete computing devices can ever exist.
Ethereum has a Turing complete language that is only limited in practice by external constraints like the gas limit. Bitcoin doesn't have such a language.
The EVM is TC in that you cannot determine if a snippet of code will halt, given sufficient gas. EVM code is undecidable, whereas Bitcoin script is not.
[1] https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3160279
[2] https://coingeek.com/bitcoin-script-is-turing-complete-scryp...
[3] https://www.youtube.com/watch?v=M6j-11H2O7c