It is surprising though that Portalon clusters with Tuscans
I don't think that a speculation that he is "eastern" admixed is out of line. Whether this is some sort of early diffusion west of "Indo-Europeans" I don't know. It is interesting in that regard that Tuscans can probably be modeled as Sardinians to which you add an "Indo-European" component.
Nor do I know if this has anything to do with the culture that built La Bastida, the Bronze Age fortress in Murcia. There are tantalizing hints that there are similarities with one of the levels at Troy, and the culture certainly exhibits marked differences with the prior Neolithic cultures of Europe.
This is an article that gives a general overview of a 2012 paper:
http://www.eurekalert.org/pub_releases/2012-09/uadb-lb092712.php
There is a more recent 2014 academic study on the subject:
the la Bastida fortification: new light and new questions on early Bronze Age societies in the western mediterranean
V Lull, R Micó, C RIHUete, R Risch - Antiquity, 2014
You can find a link to the PDF on this page:
https://scholar.google.com/scholar?start=10&q=La+Bastida,+Murcia&hl=en&lr=lang_en&as_sdt=0,33
"avalanche" = fleeing - why not? but the other Greying Wandering's hypotehsis about precious metal in Iberia could be sufficient:
I have not red yet entirely the La Bastida story (I read slowly on a screan) but I remember that in El Argur culture sites, since 2200 BC appeared the first individual sepultures (or their generalization, sometimes with a second person inhumed) under tumulus, replacing the collective sepultures of old times, with dead people inhumed into big urns, and this mode of sepulture was very common during Bronze Age in Near Eastern and, very rarely, in Bohemia, where it could be of foreign origin (I recall the Unetice Culture, later, shew also what could considered as a patchwork of cultures, where diverse influences were not always completely smelt one together) - so people come from East in Iberia at bronze Age, surely, not only artefacts, for I think -
fleeing is possible, nevertheless: some pertirbations at these dates - 2200 BC: brutal end of Los MIllares culture complex and destruction of Troia II in East...