Aside from being untrue or at least exaggerated with respect to the timeframe of the requested delay, the purported reason for Lindsey's firing (asking for a delay of the 2018 tour) contradicts how the band treated Stevie's similar request in 2012.
It’s clear from this interview that Fleetwood Mac had been planning to tour in 2012, but Stevie then decided to tour instead with her solo band (co-headlining with Rod Stewart) and to delay the Fleetwood Mac tour to 2013:
https://www.youtube.com/watch?v=ozXM_SjnfcE (1:30 mark)
This makes it all the more farcical for her and the rest of the band to suggest that no member has the right to ask the others to push back their collective tour plans.
Also, since Stevie used Brett Tuggle for her tour, she left Lindsey without his righthand man and put him in the position of not being able to tour with his own band (although Lindsey may have been just fine with that, and in fact eager to try a true solo show as he did in 2012).