That's how UMAX got around Apple's refusal to certify PowerPC 750-based clones: they made upgrade-capable computers, sold them either with an older 603/604 or no processor at all, and threw a G3 upgrade card in with the package. That way they were selling already-certified hardware with a separately-boxed user-installable upgrade as a package deal.
If Apple can use a loophole to force the clone vendors to renegotiate the Mac OS licensing scheme, then UMAX can use another loophole to sell G3-based computers without having Apple certify them as such.