There is absolutely nothing wrong with using a spoon when forks or knives are not available. In fact, using a spoon as a substitute for utensils like forks and knives is a common practice in many cultures and situations.
Spoons can be quite versatile and can serve multiple purposes beyond just scooping up liquids or soft foods. They can be used to cut softer foods, push food onto a fork, or even assist in tearing apart certain foods. In some cultures, people traditionally eat with spoons, and in others, spoons are used as the primary utensil for most meals.
The appropriateness of using a spoon in place of a fork or knife largely depends on the type of food you are eating and the cultural context. In informal settings, using a spoon creatively to manage different foods is entirely acceptable. In more formal settings, you might need to adapt your eating habits to match the etiquette of that particular culture or environment.
Ultimately, it's essential to remember that dining etiquette can vary widely across different cultures and social settings. The most crucial factor is to be respectful and mindful of the norms and practices of the situation you find yourself in. If a spoon is the only utensil available, feel free to use it as creatively as necessary to enjoy your meal!