Was there a non-IE ablaut in Proto-Germanic?

Boutkan (1999) makes an interesting argument that many Proto-Germanic lexemes of unknown etymology show an unusual ablauting pattern.

AblautPG(1)PG(2)PG(3)Notes
1.*a ~ *a: ~ *o:*hak-*ha:k-*ho:k-
2.*iT ~ *uT*hakid*hakudPG *hak- + -i/ud
*krabiTcf. PG *krabb
3.*-k- ~ *-g-*ha(n)h-*hu(n)k-*-k- > *-h- & *-g- > *-k- due to Grimm's Law
4.Nasalization*hVk-*hVnk-Nasal pattern in Rows 1 & 3. Finnish hanka is not from PG but shows same nasal pattern.
5.*a ~ *æ ~ *o:*mas-*mæs-*mo:s-
6.*a ~ *æ*mag-*mæg-This pattern possibly a subset of pattern #5
*haringa-*hæringa-
*dwas-*dwæs-
*fat-*fæt-
*skatt*skæt(t)-Possible.
7.*a ~ *o:*hatt-*ho:d-This pattern possibly a subset of pattern #5.
*klak-*klo:k-
*knast-*kno:st-
*kak-*ko:k-
*laP(P)-*lo:f-
*lam-*lo:m-
*was-*wo:s-*we(i)s-Third example problematizes things.
*skath-*sko:th-Adjective

Boutkan's argument was savagely panned in Kroonen's The Proto-Germanic n-stems. He wrote,

Even though the isolation of substrate features is a legitimate approach to the investigation of contact with unknown languages, [Boutkan's] methodology was focused on the wrong features in Proto-Germanic. As such, the Substrate Theory can hardly be seen as anything else than a tragic injury against Germanic studies. (pg. 130)

Is there a burn center nearby?

Boutkan, Dirk. "Pregermanic Fish in Old Saxon Glosses: On Alleged Ablaut Patterns and Other Formal Deviations in Germanic Substratum Words" in Speculum Saxonum. Ed. by Arend Quak. Rodopi. 1999.

Kroonen, Guus. The Proto-Germanic n-stems: A study in diachronic morphophonology. Rodopi. 2011.