We think that they can either suck it up, or keep using they as it clarifies very much the thesis. And by they I mean you, by we I mean they, or something like that.
I wrote my PhD thesis by putting "I" everywhere when the norm was a vaporous "we, the people". I wrote it, together with MY brain and, most importantly, MY ego. The dog did not type it either, though we could be all-encompassing.
I find it ridiculous to use a metaphorical "we" or "they", or "the neighbour" when talking about one's own work. We should share their salary, while we are at it.
Now youyour question is whether you can do something or not, which is completely up to the jury or referrer. Sure you can. And sure they can make your life miserable.