Re: Exodus Definition & Meaning Merriam-Webster https://www.merriam-webster.com › dictionary › exodus

ah, yes, the use of language without regards to connotations justified by selective dictionary citation....

the full content of the definition at the link is:
exodus
noun
ex·​o·​dus ˈek-sə-dəs ˈeg-zə-
Synonyms of exodus
1
capitalized : the mainly narrative second book of canonical Jewish and Christian Scripture
see Bible Table
2
: a mass departure : emigration

hint: you are overlooking "mass".
for coaching staff departures to constitute an "exodus" they would need to be in remarkably larger numbers than is typical (these aren't) and have as a cause something characteristic of the biblical exodus: escaping a bad situation (again, these aren't)