What you linked to is actually a beer dispensing system and not kegertor While 5 liters may seem like a nice volume, these are really single party day sizes. They use CO2 cartridges, which is convenient, but they will only keep the beer fresh for more than a day or two (some people can keep them in a refrigerator for up to a week, but thats about it)
There are real kegerators that use CO2 canisters (usually 5lbs). While the idea of a full keg or a 5 gallon corney keg may be too much, the good news is that these kegs now come in mini sizes like the 1.5 gallon torpedo keg and the 1.75 gallon cannonball keg.
The advantage is that they are already fitted with the standard ball lock valve for very easy connecting and disconnecting.
They can be filled like any growler at your local tap house that fills growlers. They might look at you strange but once you explain your mini keg is actually a growler they will get the idea.
When you get home, you add CO2 then purge it by lifting the relief value. You do this two or three time to remove whatever air was in there since oxygen is beer's enemy. Since these require air pressure to properly seal the lid, the drive home needs to be direct and steady. Since the beer is already carbonated, after purging the oxygen, set the regulator at dispensing pressure (about 10lbs but that is another chart) and relief the excess pressure.
drink
Kegerators can come with either the standard tapping systems (the classic commercial keg center tap) or the corney keg (for homebrewers and your case the mini kegs). Don't worry of you find one that has the commercial tapping lines, the fittings can be easily cut off and refitted with the quick release ball valves (coney kegs). Just be aware there are two types.
If he decides to venture into home brewing, he'll be all set to keg his own brew,