They don't have ".com" domain or trademarks.
Their product solves a problem in a similar domain but does not have an overlapping user base.
I am not concerned about SEO – the SaaS tool I have in mind will not acquire users through search results.
What else is worth considering?
Doesn't mean you can't use the name. Perhaps the name is generic or sufficiently descriptive of what the software does that it can't get trademark protection. Or maybe your product is so different that there wouldn't be a likelihood of confusion.
Can't answer that question in a vacuum (don't know the mark, how they are using it, how you plan to use it). But assuming they have no trademark rights is dangerous.