A small pluggable puncture won't damage the tyre carcass. In tyre sealants do the same job as a plug so could be a solution (sic) looking for a problem.
A puncture big enough to be unpluggable won't be stopped by a sealant, but that sort of hole can rip and blow out. The advantage of a goo is slowing the decompression rate. The tyre will probably be scrap anyway but at least I would get some warning before its gone completely flat and causes a crash.
As said the Police use Puncturesafe so how harmful can it be?