A magnetic Squid fuze had to survive launch, impact, and depth

Could Squid anti-submarine mortar bombs have used magnetic fuzes?

In theory, but making a magnetic fuze survive mortar launch, water impact, and descent reliably was the central obstacle.

A magnetic fuze was theoretically possible, but it had to survive being fired from a mortar. It then had to endure air travel, violent water entry, and descent to operating depth before detecting the submarine correctly. Every transition created another opportunity for a delicate sensor to fail or detonate incorrectly. That reliability burden explains the preference for simpler impact, time, and depth arrangements.