Nope because the lock icon is used for other elements, eg. when you close a topic:
In your case you need to target very specific elements, so you need to use the good old CSS instead of change the icon globally through the APIs.
Something like this should work:
.category .badge-category.clear-badge.restricted .d-icon-lock,
.badge-category.clear-badge.restricted .d-icon-lock,
.category-list .category-text-title .d-icon-lock {
display:none;
}