This is all hearsay, but the beard story I heard was slightly different. The beard drastically reduced Mifune's options for fill in work (e.g. commercials, roles in other movies) and Kurosawa wouldn't allow him to shave it off.kinjitsu wrote: "Desperate for income, he signed to do a television commercial for a pharmaceutical film, but still had that beard. Kurosawa feeling the beard was, in essence, partly his, didn't want Mifune to do it."
But I think you're right that the real story runs deeper. It seems to me that Mifune (rightly) resented being taken for granted to such an extent that it compromised his ability to earn a living; and Kurosawa resented the resentment. And Kurosawa at least (but probably both of them) was too proud to mend any fences later on.