More in detail, he reconstructs how Vācaspati (probably, I would add, since there is always the chance of a shared background of live discussions, what I call “interlanguage”) derived some of his anti-apoha arguments from Sucarita:

1. First, both Sucarita and Vācaspati follow Kumārila in starting their rebuttal of apoha by questioning its locus (āśraya, “reference” in linguistics). If this is a vikalpa ‘unreal conceptual construction’, then how does it come that I keep on understanding the same thing when I hear the word “cow”? If the reference is as ephemorous as an erroneous concept, the meaning of the word should change without interruption. Kataoka’s argument is strengthened by the fact that Jayanta, the other early-but-post-Dharmottara opposer of apoha, uses a different strategy.
2. both Sucarita and Vācaspati note that apoha cannot at the same time express something positive (vidhirūpa) while only being a conceptual construction (kalpita). Here Kataoka is on a less sure ground, given that the problem of the contrast between the negative nature of apoha and the fact that it seemingly expresses positive (vidhirūpa) entities had already been noted by Jayanta (NM, apohadūṣaṇa, sections 2 and 3.1 of Kataoka’s edition), but it is also true that Jayanta does not juxtapose vidhirūpa and kalpita.
3. Last comes an interesting point. Sucarita and Vācaspati agree in describing Dharmottara’s position as descriving the word-meaning as something conceptually constructed and ultimately false (alīka). However, in a later passage Vācaspati uses a more complex term, namely alīkabāhyatva. This might be an evidence of the fact that Vācaspati was following Sucarita (and not the other way round), but incorporated a term which had just been introduced in the debate (possibly by Jñānaśrīmitra, who speaks of āropitabāhyatva).

This last point is convincing as for the relative chronology of Sucarita and Vācaspati, but I must admit that I am not sure I understood what is conceptually at stake in this terminological change. Does it mean that Sucarita is just speaking of the apoha as false, whereas Jñānaśrīmitra speaks of this falsity as appearing as if it were external? If so, then this seems to be just another way to state Dharmottara’s position that apoha is neither internal nor external, but rather an internal construction which appears as if it were external (kaścid āropita ākāraḥ). Jñānaśrīmitra and Vācaspati may have introduced a terminological novelty, but I am not sure whether there was also a conceptual novelty beyond it.

Do you identify a development in the apoha theory after Dharmottara?
For another post on Kumārila’s commentators, see here. On Dharmottara’s position on apoha, see here and here. On apoha you might also enjoy this post.