This kind of processes would be mediated by flavor changing neutral currents forbidden in the standard model. TGD predicts exotic gauge bosons inducing this kind of processes. In TGD framework flavor is due to the topology of the wormhole throat at which the fermionic quantum numbers reside (see this and this). Fermions correspond to CP2 type vacuum extremals topologically condensed to the background space-time sheet and there is only single wormhole throat. At the throat the induced metric changes its signature from Euclidian to Minkowskian so that the orbit of wormhole throat defines a light-like 3-surface. The topology of the wormhole throat in orientable case is characterized by genus (handle number) so that one obtains sphere, torus, sphere with two handles, etc... There is a nice argument explaining why just the three lowest topologies correspond to stable and light fermions.
Gauge bosons correspond to wormhole contacts-pieces of CP2 type vacuum extremals with Euclidian signature of metric connecting two Minkowskian space-time sheets. There are two wormhole throats so that gauge bosons are classified by pairs (g1,g2) of genera for throats. It is natural to arrange fermions and bosons to representations of dynamical SU(3) group which could be called flavour SU(3) but having not much to do with the ancient flavor SU(3) of Gell-Mann. For fermions/antifermions one obtains triplets/antitriplets and for gauge bosons octet and singlet as the tensor product of triplet and anti-triplet. Singlet is identified as ordinary gauge bosons and octet gives rise to exotic gauge bosons inducing flavor changing neutral currents. If the p-adic mass scale of the exotics is higher than that for standard gauge bosons, one can understand their experimental absence.
CKM mixing in TGD framework is induced by different mixings of topologies of wormhole throat in the case of U and D type quarks. In absence of this mixing the neutral flavor changing currents would change the flavor of both interacting fermions: in the recent case electron and u or c quark transforming to top quark. Already these reactions would be something completely new and could be mediated by both gluons, Z0 bosons and also by W bosons in which new kind of charged flavor changing current would be in question. CKM mixing makes possible also reactions in which only other fermion changes its flavor. In the recent case it would be quark whereas electron would transform to electron rather than muon or τ.
If the top in the wrong place is not just dirt- that is statistical fluctuation - what it very probably is - it could be interpreted as a first evidence for the existence of the predicted octet of gauge bosons inducing flavor changing transitions. Also octets of W bosons and gluons are predicted whereas the possibly detected transition would correspond to the exchange of octet Z0. Also the possibly higher rate for transitions with correlated change of flavor for electron and top (say e to τ and and u to top) could kill the proposal.