As I see it, the first sentence fails to mention that the voiceless stop follows a nasal nucleus, which is where the sonority and nasality are coming from. The glottalized nasal is a common adaptation. A colleague of mine used to introduce a glottalized nasal in similar environments when she spoke Spanish, which our instructor wanted her to "lose."

Here is my interpretation of your sentence, in which I have ADDED the nasal nuclei to the first sentence. It may not be an ideal solution, but I think it gets closer to what your author wants to say.

In (70) the voiceless stops in the loans appear to have been adapted as glottalized nasals, which preserve the sonority of the nasal nucleus. Thus, in the integration of loans, the two strategies triggered in the adaptation of voiceless consonants following nasal nuclei are formalized in this way.

Examples of "glottalized nasal":

The **glottalized nasal is not properly an ejective with simultaneous oral and glottal closure**... Figure 9 is an example spectrogram of the glottalized nasal in the word yii ...
books.google.com/books?isbn=1402013523...

**Buckley treats the glottalized nasal as basic and derives the voiced stop by rule**. He opts for this directionality since it results in a more symmetrical ...
links.jstor.org/sici?sici=0020-7071(200101)67%3A1%3C92%3ATAOKPA%3E2.0.CO%3B2-Z

**The typical Witsuwit'en glottalized nasal is postglottalized with. suprasegmentalized nasalization**, but there is also variation in the timing of ...
lsadc.org/info/pdf_files/2006_Meeting_Handbook.pdf