Install killed tensorflow install

[eafpres]

R 3.5.1
RStudio 1.1.381
used devtools::install_github("andrie/deepviz")
it decided to reinstall keras/tensorflow which broke it; it now cannot find tensorflow
I've had these install issues before w/Keras in RStudio; the issue is why does the install here try to change the already installed keras/tensorflow (esp. w/out asking)?
Fixing my keras/tensorflow is not a deepviz issue, but I wanted to point out the install behavior, which if possible it would be good to change.