I don't consider as blocked you can invest in markets, funds, etc. Keeping 250K in cash will lose value over time. You can invest in very low-risk bond ETFs, if you don't want any risk.
Actually, you can't withdraw money from UBS AE, you can withdraw from︅ Zurich. UBS AE is the representative office of UBS AG(Switzerland). If you open an account︆ via UBS AE that means you have an account in Switzerland.
If you have Standard Chartered or DBS branch/office in your country then︊ you can open remotely. I can open SC SG or DBS SG account from Dubai.︋