Yeah, and what about the value of production hardware and infrastructure? (Stuff not being sold/transferred to customers.)
For example, imagine a company with very little proprietary code because they focus entirely on renting out their CPU/GPU/disk capacity, for supercomputing, databases, render-farms, cloud backup, etc. I'd still call that a "tech company."
It's also not clear how this "intellectual property of the source code" angle would accommodate the network-effects or value of a subscriber-base... Well, I suppose you could argue that such an asset doesn't require high-tech means, it could all be snail-mail.
Texas Instruments' value is mostly in their integrated circuits IP (as well as manufacturing prowess, process knowledge, and a little bit of software). They're still solidly a "tech" company in my books.