Did they perhaps mean "modular" in the sense of the computer being composed out of a set of standardized modules, with none of the modules having been constructed for that computer alone?
Not just component-wise upgradability or ease of assembly, but rather eliminating entirely the concept of doing one-off "integrations" to create new products in the line. In other words, doing with their computer parts what IKEA does with furniture parts: designing and manufacturing only at the component level, then feeding all the finished components into a shared pool of resources, where products are then simple assemblies of resources from the pool.
I'm a bit late to reply, but the idea of IBM's modular SMS cards (1950s-1960s) was that they would create a relatively small number of these cards and would build computers out of them. (A card might have a few AND gates for instance.) In practice, new machines required custom cards and IBM ended up producing thousands of different SMS cards. So the idea was only semi-successful.
Not just component-wise upgradability or ease of assembly, but rather eliminating entirely the concept of doing one-off "integrations" to create new products in the line. In other words, doing with their computer parts what IKEA does with furniture parts: designing and manufacturing only at the component level, then feeding all the finished components into a shared pool of resources, where products are then simple assemblies of resources from the pool.