They're a company that builds stuff for customers. So if they want to end up on the 'short list' then they probably should sign that NDA for those customers or potential customers that require it.
If a (potential) customer wants you to sign an NDA for their peace of mind and there are no crazy claims in it then I would class that under 'no big deal'.
It's maybe surprising but the further up in that world you (sub)contract the fewer of these NDA's for peace of mind you come across. But someone who has an idea and is shopping around for a party to build it will likely have heard a bunch of horror stories about people running off with ideas brought to them by others, maybe they've seen the facebook movie, whatever.
If you can turn that prospect into a paying customer by signing their NDA then that's (usually) just fine.
One way in which you can usually strengthen an NDA to your advantage is to make sure that you never ever compete with your customers and that you declare any conflicts of interest immediately after the NDA is signed but before any material information changes hands.
If the customer then still wishes to pursue you make sure they confirm to you in writing that they are aware of the conflict-of-interest.
This happened twice in my whole career to date and I got the job anyway in both cases.