Bronze age loans from Germanic to Finnish and other things

Some (I believe among them Koivulehto) have proposed that Finnish
borrowed from Germanic already in the Bronze age. That would not be
good for my idea that Proto-Germanic as we know it entered
Scandinavia in the first century BCE.
Here is a line of argument that would support Bronze age loans (from
H. Fromm: Germanisch-Finnische Lehnforschung und germanische
Sprachgeschichte):

In Fi. <kalja-ma> "Glatt-eis", (supposedly from Gmc. *xa:l(i)ja) the
initial /k/ shows that the loan took place before the Proto-Finnic
("Urfi.") change */s^/ > /h/ which made substitution Germ. /x/ by
Balt. Finn. /h/ possible.

This argument however assumes that Grimm /k-/ > /x-/ in Germanic had
already taken place. If we assume that Grimm took place _with_ the
Thuringian/Swebian etc expansion, then the languages of Scandinavia
migh have been pre- or para-Germanic (which doesn't really mean much,
since what is Germanic without Grimm?) and loans into Finnic could
have taken place from those languages. AfaIk all those early loans
from Germanic assume that Germanic /f, T, x/ are loaned as /p, t, k/,
since Finnish did not have those phonemes. But if the donor language
instead had unshifted /p, t, k/ there would have been no Germanic /x/
to substitute with Finnish /h/, which means that the appearance
of /h/ in Finnish no longer is a terminus ante quem for those loans.

BTW I find the idea of a /f, T, k/ - using people subjecting /p, t,
k/ using people intriguing. That would have established a /f, T, k/
speaking upper class and a /p, t, k/ speaking lower class in the
Nordwestblock and East Jutland/Fyn (and Scandinavia?). When the
Thuringian/etc expanded southward they would have met people who
didn't speak related languages, so this shibboleth relationship would
not have worked. Instead, as soon as the subjugated peoples learned
to speak a smattering of the language, their new masters re-
established the difference (by the second Grimm shift) in order to
preserve the proper social structure.

Torsten