It looks more like a national security issue. If we're ever at war then the enemy can always tip over a jug of petroleum ether to turn our deeply embedded geofoam foundations into glue, which I imagine would cause everything built on top to crumble too. It would appear they're mostly building highways using this stuff (rather than skyscrapers) so that shouldn't be too much of a vulnerability but it probably isn't what Dwight Eisenhower had in mind when he built the interstates.

[1] Aabøe R, Frydenlund TE (2011) 40 years of experience with the use of EPS geofoam blocks in road construction. Paper presented at the 4th international conference on geofoam blocks in construction applications, Lillestrøm, Norway, 6-8 June 2011

What is a "long time"? Is it one human lifetime? The time period in which these blocks will be a blight is a whole lot longer than the time period where they make a nice landscape, it's just that the nice landscape part comes first. Should we do anything we want assuming that what happens after we're dead is irrelevant?

One wreck involving a fuel tanker without sufficient containment and the entire subgrade starts to dissolve and buckle and sink?