I've seen the video countless times and the man clearly ACCIDENTALLY knocks the old fellow over. It was NOT a deliberate act and you can CLEARLY see that he accidentally brushed past the man just enough to send him toppling over.
The old fellow also looks like he's had ten too many. Rather than "frail" as you called him the old fellow looks decidedly rat-arsed.
There is atrend nowadays amongst certain members of society of making mountains of molehills and showing needless faux outrage. People get drunk at Aintree all the time (most of the drunkards making prats of themselves are women nowadays) and had this occurred 20 years ago nobody would have batted an eyelid. It is just two drunkards accidentally colliding with each other. But because the incident occurred in 2015 we immediately exaggerate the whole scenario, using silly phrases like "callously pushing the frail old man over" and making a victim out of a man who is clearly as drunk as the man who accidentally toppled him over. Western society was so much more grown up in the old days.
here's what I find interesting regarding your observation...first, you make the assumption that the old guy is drunk...he has barely moved in the video until he gets pushed so you have assumed and concluded here...why would that be...well because you have chosen to defend the beef cake...since from a factual stand point he is clearly drunker than a lord, can barely stay up right and did knock the old man over, you now need to place them on equal terms...thus the old man is drunk
next: ratarsed or not he is frail compared to the big boy
so you too are assuming and exaggerating... it's just a matter of sides really if one is inclined to take sides
if it had happened 100 years ago instead of today or 20 years ago no one might have even helped the old guy...we've evolved...well, some have...you know that adage...we do the best we can for where we are...some people just aren't very far...I don't think anyone actually made a big deal out of it...he headed right for the old boy...he's a big beef cake of a guy...the old man is little and frail...did he think in his drunken brain fog "let's mess this little guy up"? ... no he didn't...