My now 9 month old son is very like this. He basically followed what MantaRay laid out: he took EBM from a sippy cup only after a lot of struggling. (Is your friend giving him the cup herself? My baby will never take one from me. Get a carer to try.) We began offering him solids in the baby led style from 6 months and I thought he would dig in. Not so. His childcare centre (who were giving him puree) said that it took him a month after that to even begin to swallow puree and he also didn't swallow the finger food we gave him until after 7 months. He is still extremely dependant on BM for most of his nutrition.

But the sippy cup (we use the Take and Toss ones, so that there's no need to suck to get milk out: he had trouble sucking on the ones with the valves) has been very helpful for getting caretakers to feed him and he is in daycare 2 days every week. And since 7 months or so his sleep has really improved, he is down to one or no night wakings too. So a baby does not have to be really switched to solids to be sleeping better, hopefully your friend's baby will improve in sleep anyway.