Not quite right. Herrera was not a candidate to be "non-tendered" a 2020 contract, because he's under contract - a guaranteed contract - through 2021, with club option (and buyout) for 2022 (and 2023, if they wanted him). The Phils are on the hook for $20.2 million, period.
You could revise this to posit that Herrera would be (and still could be) a candidate for unconditional release. But he's going to get his $20.2 million, regardless.
The questions have been about whether the Phillies could justify a release - e.g., differentiate the reasons for release from just "more punishment" - which is prohibited under the CBA, and could result in a grievance.
If Herrera were not on a guaranteed contract... in that case, I suspect a non-tender would have occurred, with the (legitimate) justification being that Herrera's just not worth the salary he would get in arbitration (he was paid $5.35 million in 2019, and would get at most a small reduction in arbitration). But since they signed him to a guaranteed multi-year contract, that's not relevant. They cannot justify releasing him to save money - they won't save money. They need a performance-based justification... and we're talking about a 28-year-old former All Star, who plays a position where the club is not "set" on somebody else. (Yes, we have hopes for Haseley, and Quinn might conceivably play a season without injury , but it's not as if Herrera has been rendered redundant by an obviously better CF.)
If Herrera performs even reasonably well in ST, my expectation is that the club will not cut him loose - they'll either trade him (along with most of the $20 million he's owed, or in exchange for some other club's $20 million problem), or send him to Allentown, where he might yet force his way back to the Phillies.