Background
My employer requires that I take training which is offered to all employees by Company-X at no cost to my employer. This training is essentially a circuit of courses that are offered at various times of the year. Once these courses are completed I am considered qualified in my specialty.
As classes scheduled for 2020 were shut down due to COVID, I was only able to complete a few online courses which were self-led classes.
There is a common consensus among my coworkers who are training me (my manager included) that being immersed in the training (courses that last longer than a week) is the best method to learn the skills I need to perform my job.
There is another Company (Company Y) that is offering a comprehensive training which will run several consecutive weeks that is of equal or higher caliber compared to what Company X is offering for free. This training will qualify me completely once finished. That being said, the training that Company Y is offering is somewhat expensive.
Problem
My manager approached me and asked me if I would be interested in taking the comprehensive training with Company Y. I indicated that I would like to enroll. They instructed me to do so.
As I was working on enrolling in this training a manager from a different group (not my manager) discovered that I was going to enroll in the training with Company Y and tried to convince me to not take the course for various reasons (e.g. that since Company X offers courses for free that it’s a waste of money for me to take the course offered by Company Y, etc.).
I communicated all this to my direct manager and they indicated that I should still sign up for the comprehensive training because they feel there is a large value in me taking the course offered by Company Y.
Question
As I am going to enroll in the course that my direct manager wants me to take, how should I handle the other manager when they inevitably approach me to ask why I took the course (i.e. Why am wasting my employers money, time, etc.)?