How likely are planets to form after neutron star collisions?
There do appear to have been some studies on the properties of potential fallback discs formed after neutron star mergers, for example:

Rosswog (2007) &quot;Fallback accretion in the aftermath of a compact binary merger
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Cannizzo et al. (2011) &quot;Fall-back Disks in Long and Short Gamma-Ray Bursts
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Lyutikov (2013) &quot;The Electromagnetic Model of Short GRBs, the Nature of Prompt Tails, Supernova-less Long GRBs, and Highly Efficient Episodic Accretion
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These studies focus on explaining X-ray flaring in the aftermath of gamma-ray bursts rather than the potential to form exotic planets in these environments. It does seem fairly likely that some kind of disc does form around the remnant of a neutron star merger, but it's going to be extremely hot and likely so close to the remnant that it will be unable to form planets.
As noted in Menou et al. (2001) &quot;Stability and Evolution of Supernova Fallback Disks&quot;, planet formation in fallback discs depends on the timescales for the disc cooling and how long it takes to spread beyond the Roche limit: if the disc becomes neutral before it spreads beyond the Roche limit, spreading becomes reliant on interactions within the remaining disc of rocks. While they consider the case of merging white dwarfs (noting that this scenario leads to a more favourable environment for planets than post-supernova fallback discs around black holes or neutron stars), they do not study the case of merging neutron stars.