Yes the alternator is likely able to charge the battery at idle, Unless he has a BIG powerful radio amp or other Power hungry thing going that uses all that the alternator can output at idle. Even then, we'd need about 30 min run time to put back what it takes to start Each time we crank the engine. SO, even if he idled 30-60 min at lunch, he'd still have a charge deficit after starting to come home.

Idling the engine = Zero mpg, so isn't an economical way to charge a battery & adds insult to injury that this Super Severe short trip service is doing to the engine & oil, from moisture & combustion by-products causing sludge & acids in the crankcase that'll deplete the oils base number & detergent / dispersant additive package. SO, lets think about this some more as there's Lots going on here besides battery abuse.

Consider having him invest in a Temperature Compensating, Smart / micro-processor controlled battery charger like the Clore PL2310 here 10/6/2 Amp 6/12V Intelligent Battery Charger / Maintainer - Clore Automotive & let it Slowly recharge the battery Overnight on the 2 or 6 amp charge rate & the battery will last a Lot longer, so the charger can pay for itself over time.

l agree have him take it for a 20 mile non stop Highway run once a week, to get the oil up to Full operating temp long enough, to evaporate crankcase condensation & fuel dilution, as it'll help the engine & oil last longer & it'll also have the alternator top up the battery charge that day.

If he doesn't want to do that, let him pay for the batteries & feel the pain, or let him Walk to work & back, 1/2 mile each way isn't far, so is good exercise & helps with attitude adjustment !!!! lol
A bunch of thoughts for consideration, let us know how it goes.

 

that's what I was thinking, he lives in a huge apartment complex so no way to put a charger on it, was thinking about a solar charger?

 

Solar, well lets think about this some more. They don't work at night nor well on cloudy days, so he'll need a sizeable array to be able to put enough charge back in over a 8 hour work day & to make up for the morning start + the previous day return home start, + vehicle systems overnight computer / controller parasitic memory drain on the battery. SO, size the array wattage to allow for poor charging weather, array positioning angle for best available sun charge at this time of year, array stated efficiency & amp drain needed to be replaced over the work day. For example if we want to recharge at say 4amps over a 8 hour work day - 4x8=32amp hours, we'd need at least a 48 watt array (4amps x 12 volts = 48watts) operating at 100% efficiency & none are, so opt for More wattage, to make up for the published array efficiency difference below 100%, so the charge is completed in the needed time.
Then be sure to opt for an array that is regulated, so it wont Over charge, nor Discharge the battery at night or cloudy days, when array voltage is Below battery voltage. All that'll cost $$$, so a long extension cord & the Amazon $60 Clore Pro-Logix PL2310 temp compensating charger is looking like a pretty good investment. Or, to save on the cost of a long extension cord, have him remove the battery for charging in the apartment.
More thoughts for consideration.