Core Pathways of Aging is background reading that explains why transposons are an issue.
There are two types of transposons. Class I TEs or retrotransposons generally function via reverse transcription, while Class II TEs or DNA transposons encode the protein transposase. I can't think of a good way of attacking retrotransposons which don't produce any proteins.
On the other hand, DNA transposons can be attacked because they need express transposase to copy themselves. When we vaccinate against a particular type of transposase our immune system will start to attack all cells that express the transposase, because cells present fragments of the transposon on their cell wall.
PGBD5 is expressed in the majority of pediatric solid tumors. While a tumor can mutate in a way that shuts off antigen presentation it's possible that PGBD5 gets expressed in the beginning of the lifecycle of pediatric cancer. While we are at it
Given that we don't know whether some cells have valid reasons for expressing PGBD5 it makes sense to not self-vaccinate and wait for clinical trials, but the potential of a cheap way to increase longevity and reduce cancer risk seem to me worth the effort.