This wasn't on the frontline, the guy on the right has his safety catch on. Why is Assad pictured and quoted, and nobody from the opposition is? The Syrian Observatory for Human Rights has been questionable in some of its reporting often omitting to mention Free Syrian Army involvement on the rebel side, and I think it accepts exaggerated figures for government losses, allowing Patrick Cockburn to claim in 2013, while calling the SOHR pro-opposition, that the rebels were killing more people than Assad. I can't find any more details about this on their website, but clearly the Guardian doesn't care to divide the groups according to whether they fight Assad or not, and give any idea who 'the rebels' are.
"More than 15,000 rebel fighters were killed, as were nearly 17,000 militants from jihadi groups, including Islamic State and al-Nusra Front, al-Qaeda’s Syrian affiliate."