1 MV62 Command-Link Drone and up to 2 MV52 Shield Drones."
It is clear that 3 is max from before. The "and up to" COULD refer to just the shield drones. Although I'd argue 0 shield drones could be chosen, it is possible to argue it says 2-3 drones total (1 of each being mandatory). This is by just looking at the wording here and not taking into account rulings with similar wording I am unfamiliar with or other places in codex/rules.
It could also be implied to the sentence as a whole, since there is no full break or "," dividing the semantic reference. In this case all drones would be optional with max values for each type (1 & 2 for a total not exceeding 3).
Similar word rulings since before is probably the closest one will get.
If I played another army and the opponent tau showed me it asking for ok to go with their list, I would not mind. If forced to make a ruling with no more data, I'd say 1 + 0-2 for 1-3 drones.