The safety culture of the US railways and their lack of TPWS/AWS etc esque systems is rather shocking when compared to European railways.
A lot of the US East Coast commuter railways do have safety systems in the form of pulse coded track circuits:
https://en.wikipedia.org/wiki/Pulse_code_cab_signaling
These date back in principle to the 1920s and were pioneered by the Pennsylvania RR. They transmit speed codes based on signal aspects, including a '0' code, i.e no signal which means 'restricting' a speed limit of 20 MPH, so not a trainstop as such. Some but not all RRs also use the same system to encode and protect fixed speed restrictions as well. It was the lack of the latter that contributed to a series of 'speeding on curve' incidents in the last few years and Amtrack and Metro North were forced to retrofit a number sites with this old tech just when the're also gearing up for the big PTC changeover as well. To be fair signal engineers were able to do this within days so it begs the question why authorities were so adamantly opposed to doing the same at high risk sites before. Perhaps it was the 'planning blight' of an all new all singing and dancing system 'just around the corner'?
Anyway I know nothing concrete about buffer stop protection here, only that even a fairly low speed collision with typically heavy US rolling stock will have to dissipate an awful lot of energy. I believe there are coded tracks in the area as NJ transit services are mostly over former PRR trackage that I know was widely fitted from the early days and the WIki page linked above states the entire NJ system is fitted. I suspect there will be no code in the platform, corresponding to a 'restricted' 20 MPH limit, but there will be no further check as the train approaches the bumper, unlike our '5 MPH' buffer stop TPWS loops. If the brake system itself failed in some unexplained wrong side manner however, then even higher approach speeds may have been possible, but even at up to 20MPH the energy involved would have been significant. We shall have to wait and see what investigators reveal.