It is a truism that political and economic uncertainty is the enemy of business. That's because the "not knowing" makes it impossible for business to plan for the future.
The uncertainty (and therefore the "fear") in this case is caused by the government's failure to commit itself to a positive course of action. A positive course of action removes the uncertainty. And that is true whether one thinks the policy is economically advantageous or otherwise.
Let's take a bad case for a low tech company (nothing to do with Brexit) if a Corbyn government came in and announced a 50% rise in the minimum wage. The company can plan for that. It can work out how to reduce its staff. It can look at the possibility and costs of automation. After all that it may end up going out of business, but it has had the chance to consider work-arounds for legislation which would prejudice its business in the short term. The speedier mammals would survive.
And, back to Brexit, let's take a bad case for a high tech company: a "hard Brexit" which will raise the price of the components it imports from the EU and will make the price of its final product more expensive for its EU customers. This company, too, can plan for that. It can look for cheaper suppliers, and alternative markets outside the EU. Or - and businesses have been known to do this - it can arrange "deals" with its major clients to "avoid" the extra costs. And after all of that it may still go out of business. But not all such companies. The nimblest will survive.