Fox switching seats was probably two-fold. Yes, it ices GO1 a bit and gives Fox some time to think. You see stuff like this all the time in tournaments, but it’s usually more in the form of players going back to character select and taking their time there; making it look like they’re thinking about switching characters or just taking their sweet time picking their colors. Players are often given the same advice: stop just mashing “rematch” if you’re getting blown up. You need to stop the momentum and think about why you’re losing.
More importantly in this case though I think it was a technical thing. Fox’s new team is a fairly recent switch for him, so I can see him being more comfortable on P1 side right now. The thing with his team is that (much like GO1’s pre-nerf Adult Gohan team) it involves what is essentially a permanent block string–that is, of course, assuming he doesn’t mess it up.
Characters will rarely switch sides BEFORE a hit happens in a fighting game, so by starting on P1 side, a side that he feels more mechanically solid on, Fox has a much higher chance of executing that block string. This means that he’s less likely to mess up his pressure, which with his team set up is the only way that it would ever stop (unless GO1 manages to block for ~25 seconds, which he did once or twice.) And because in DBFZ when a character dies everything resets back to that neutral position, Fox gets to just start the process from the beginning.
Get opponent to block -> pressure forever until you get a hit -> end combo with a level 3 super to get a knock down -> you’re at advantage, so you repeat the process with a mix up on wake up (your opponent gets one Get Out of Jail card here if they have sparking) -> get a 2nd combo to kill a character -> back to neutral -> repeat.
This has been the DBFZ meta since GO1 showed up and rolled over everybody with A. Gohan months ago. The game’s lack of defensive options make this the absolute strongest meta for technically proficient players. Nobody can block forever, but in this game you often don’t have a choice; reflect isn’t good enough, and for whatever reason they chose not to include any of the instant block, barrier block, push block, or burst mechanics that you usually see in other games.