it's not that they weren't racist. they were racist, clearly, and especially when they were younger. but, stop for a second and imagine living in a reality where everybody is racist.
it's not that it was just business. it's not that the times were different. it's that everybody was racist - and that ridiculous displays of overt racism were normal. so, people express the norms that they are raised into - and jefferson and washington both did, absolutely. for that reason, they were both racist.
but.
jefferson, especially (although also washington, later in his life) were amongst the first members of the aristocratic class to wake up and realize just how horrific what they were doing really was. and, before you can take steps to make changes, you have to actually realize the need to do so.
so, when i stand up for jefferson particularly (and washington less so), it's really not meant to whitewash the truth - they owned slaves, they were racist. it's just to point out that they were amongst the first to question the system as it existed, and that we might still have slavery, if they hadn't asked those questions and put in motion some of the first steps to end it.
it's subtle. but, it's a part of understanding how we got here to realize that, in the larger unfolding of history, some of those guys were really on your side.