Plenty are ashamed which is why they don’t speak it. If your parents are illiterate and don’t speak English, there’s no excuse not to know Somali.
There’s a difference between proficiency and native fluency. Also native speakers will always notice your accent but it doesn’t mean you’re not fluent. It’s definitely possible living in the west, you just need intensive immersion.
Are you saying someone who grew up in the diaspora can be fluent but will always have an accent that cab be perceived by those in from/in Somalia?