I have a Mobell (same company as Mobal) UK sim that I got years ago, very convenient, phone bills charged to my credit card, rather than having to keep track of the balance and "top up". However, calls are relatively expensive although I don't mind for the convenience and limited use when I'm in the UK. Knowing full well it would cost me, about a £ a minute because I was in Italy, I allowed a British friend who was meeting me in Italy to call me when she arrived using her UK phone and my UK sim. I don't recommend it for more than a call or 2.
If usage will be very limited, it hardly matters. But if your friend wants to feel free to make calls regularly, they should consider doing it as locals do, as I described above and get phone & sim after arrival.
I love having my phone that I know I can use cheaply wherever I go. It's also a souvenir of my time in India. Theirs would be a very useful keepsake from their time in Morocco. I'm all in favor of useful souvenirs. Phones and kitchen gadgets.